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The 1999 season’s official transaction log: 973 trades, signings and releases involving major-league clubs, listed newest first.
| Date | Type | Player | From | To | Details |
|---|---|---|---|---|---|
| Dec 31, 1999 | Signed as free agent | Hector Mercado | — | Cincinnati Reds | Free agent signing |
| Dec 30, 1999 | Signed as free agent | Rich Becker | — | Oakland Athletics | Free agent signing |
| Dec 30, 1999 | Signed as free agent | Scott Service | — | Oakland Athletics | Free agent signing |
| Dec 29, 1999 | Signed as free agent | Kenny Rogers | — | Texas Rangers | Free agent signing |
| Dec 28, 1999 | Signed | Franquelis Osoria | — | Los Angeles Dodgers | Amateur free agent signing |
| Dec 27, 1999 | Signed as free agent | Jeff Branson | — | Los Angeles Dodgers | Free agent signing |
| Dec 26, 1999 | Signed | Juan Dominguez | — | Texas Rangers | Amateur free agent signing |
| Dec 23, 1999 | Signed as free agent | Joey Eischen | — | Cleveland Indians | Free agent signing |
| Dec 23, 1999 | Signed as free agent | Sang-Hoon Lee | — | Boston Red Sox | Free agent signing with first major-league team |
| Dec 23, 1999 | Released | Javier Martinez | Pittsburgh Pirates | — | Release |
| Dec 23, 1999 | Signed as free agent | Jose Mercedes | — | Baltimore Orioles | Free agent signing |
| Dec 23, 1999 | Signed as free agent | Bill Selby | — | Cleveland Indians | Free agent signing |
| Dec 23, 1999 | Signed as free agent | Ruben Sierra | — | Cleveland Indians | Free agent signing |
| Dec 23, 1999 | Trade | Roger Cedeno | New York Mets | Houston Astros | Trade |
| Dec 23, 1999 | Trade | Octavio Dotel | New York Mets | Houston Astros | Trade |
| Dec 23, 1999 | Trade | Kyle Kessel | New York Mets | Houston Astros | Trade |
| Dec 23, 1999 | Trade | Derek Bell | Houston Astros | New York Mets | Trade |
| Dec 23, 1999 | Trade | Mike Hampton | Houston Astros | New York Mets | Trade |
| Dec 22, 1999 | Signed as free agent | Ricky Bones | — | Florida Marlins | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Kane Davis | — | Cleveland Indians | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Jeff Fassero | — | Boston Red Sox | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Buddy Groom | — | Baltimore Orioles | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Thomas Howard | — | St. Louis Cardinals | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Gary Knotts | — | Florida Marlins | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Bronswell Patrick | — | Florida Marlins | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Mandy Romero | — | Cleveland Indians | Free agent signing |
| Dec 22, 1999 | Signed as free agent | Mark Smith | — | Florida Marlins | Free agent signing |
| Dec 22, 1999 | Trade | Hideki Irabu | New York Yankees | Montreal Expos | Trade |
| Dec 22, 1999 | Trade | Jake Westbrook | Montreal Expos | New York Yankees | Trade |
| Dec 22, 1999 | Trade | Brandon Pernell | San Diego Padres | Chicago Cubs | Trade |
| Dec 22, 1999 | Trade | Dan Serafini | Chicago Cubs | San Diego Padres | Trade |
| Dec 22, 1999 | Trade | Wally Joyner | San Diego Padres | Atlanta Braves | Trade |
| Dec 22, 1999 | Trade | Reggie Sanders | San Diego Padres | Atlanta Braves | Trade |
| Dec 22, 1999 | Trade | Quilvio Veras | San Diego Padres | Atlanta Braves | Trade |
| Dec 22, 1999 | Trade | Bret Boone | Atlanta Braves | San Diego Padres | Trade |
| Dec 22, 1999 | Trade | Ryan Klesko | Atlanta Braves | San Diego Padres | Trade |
| Dec 22, 1999 | Trade | Jason Shiell | Atlanta Braves | San Diego Padres | Trade |
| Dec 21, 1999 | Signed as free agent | Frank Castillo | — | Toronto Blue Jays | Free agent signing |
| Dec 21, 1999 | Signed as free agent | Tripp Cromer | — | Houston Astros | Free agent signing |
| Dec 21, 1999 | Released | Ryan Jackson | Seattle Mariners | — | Release |
| Dec 21, 1999 | Signed as free agent | Arthur Rhodes | — | Seattle Mariners | Free agent signing |
| Dec 21, 1999 | Signed as free agent | Jon Shave | — | Texas Rangers | Free agent signing |
| Dec 21, 1999 | Signed as free agent | Brian Smith | — | Pittsburgh Pirates | Free agent signing |
| Dec 21, 1999 | Signed as free agent | Claudio Vargas | — | Florida Marlins | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Edwin Diaz | — | Texas Rangers | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Giomar Guevara | — | Detroit Tigers | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Ricky Gutierrez | — | Chicago Cubs | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Stan Javier | — | Seattle Mariners | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Randy Knorr | — | Pittsburgh Pirates | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Tim Laker | — | Pittsburgh Pirates | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Graeme Lloyd | — | Montreal Expos | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Mark McLemore | — | Seattle Mariners | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Jim Poole | — | Detroit Tigers | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Todd Rizzo | — | Minnesota Twins | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Clint Sodowsky | — | Kansas City Royals | Free agent signing |
| Dec 20, 1999 | Signed as free agent | Kevin Tolar | — | Detroit Tigers | Free agent signing |
| Dec 20, 1999 | Signed as free agent | B. J. Waszgis | — | Texas Rangers | Free agent signing |
| Dec 20, 1999 | Trade | Fernando Vina | Milwaukee Brewers | St. Louis Cardinals | Trade |
| Dec 20, 1999 | Trade | Juan Acevedo | St. Louis Cardinals | Milwaukee Brewers | Trade |
| Dec 19, 1999 | Signed as free agent | Gerald Williams | — | Tampa Bay Devil Rays | Free agent signing |
| Dec 18, 1999 | Signed | Kazuhiro Sasaki | — | Seattle Mariners | Amateur free agent signing |
| Dec 18, 1999 | Signed as free agent | Pedro Swann | — | Atlanta Braves | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Nate Bland | — | Los Angeles Dodgers | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Rick DeHart | — | Los Angeles Dodgers | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Orel Hershiser | — | Los Angeles Dodgers | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Andy Larkin | — | Chicago Cubs | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Julio Mosquera | — | New York Yankees | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Greg Myers | — | Baltimore Orioles | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Yorkis Perez | — | Philadelphia Phillies | Free agent signing |
| Dec 17, 1999 | Released | Scott Service | Kansas City Royals | — | Release |
| Dec 17, 1999 | Signed as free agent | Scott Servais | — | Colorado Rockies | Free agent signing |
| Dec 17, 1999 | Signed as free agent | Chris Turner | — | New York Yankees | Free agent signing |
| Dec 16, 1999 | Released | Darren Bragg | St. Louis Cardinals | — | Release |
| Dec 16, 1999 | Signed as free agent | Jim Bullinger | — | Los Angeles Dodgers | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Jeff Conine | — | Baltimore Orioles | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Tom Evans | — | Texas Rangers | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Chuck Finley | — | Cleveland Indians | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Shawn Gilbert | — | Los Angeles Dodgers | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Jose Hernandez | — | Milwaukee Brewers | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Aaron Holbert | — | Boston Red Sox | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Mike Hubbard | — | Cincinnati Reds | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Brent Mayne | — | Colorado Rockies | Free agent signing |
| Dec 16, 1999 | Signed as free agent | Allen McDill | — | Detroit Tigers | Free agent signing |
| Dec 16, 1999 | Trade | Brian Stephenson | Chicago Cubs | Los Angeles Dodgers | Trade |
| Dec 15, 1999 | Signed as free agent | Raul Casanova | — | Colorado Rockies | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Elmer Dessens | — | Cincinnati Reds | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Mike Fetters | — | Los Angeles Dodgers | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Joe Girardi | — | Chicago Cubs | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Rick Greene | — | Minnesota Twins | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Mike Matheny | — | St. Louis Cardinals | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Adam Melhuse | — | Los Angeles Dodgers | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Carlos Mendoza | — | New York Mets | Free agent signing |
| Dec 15, 1999 | Signed as free agent | John Olerud | — | Seattle Mariners | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Tomas Perez | — | Philadelphia Phillies | Free agent signing |
| Dec 15, 1999 | Signed as free agent | Ryan Thompson | — | New York Yankees | Free agent signing |
| Dec 15, 1999 | Trade | Dante Powell | Arizona Diamondbacks | St. Louis Cardinals | Trade |
| Dec 15, 1999 | Trade | Luis Ordaz | St. Louis Cardinals | Arizona Diamondbacks | Trade |
| Dec 15, 1999 | Trade | Sean McNally | Kansas City Royals | Florida Marlins | Trade |
| Dec 15, 1999 | Trade | Todd Dunwoody | Florida Marlins | Kansas City Royals | Trade |
| Dec 14, 1999 | Signed as free agent | Alex Cabrera | — | Arizona Diamondbacks | Free agent signing |
| Dec 14, 1999 | Signed as free agent | Wil Cordero | — | Pittsburgh Pirates | Free agent signing |
| Dec 14, 1999 | Signed as free agent | Brian Johnson | — | Kansas City Royals | Free agent signing |
| Dec 14, 1999 | Trade | Dan Naulty | New York Yankees | Los Angeles Dodgers | Trade |
| Dec 14, 1999 | Trade | Nick Leach | Los Angeles Dodgers | New York Yankees | Trade |
| Dec 14, 1999 | Trade | Adam Everett | Boston Red Sox | Houston Astros | Trade |
| Dec 14, 1999 | Trade | Greg Miller | Boston Red Sox | Houston Astros | Trade |
| Dec 14, 1999 | Trade | Carl Everett | Houston Astros | Boston Red Sox | Trade |
| Dec 13, 1999 | Released | Jose Fernandez | Montreal Expos | — | Release |
| Dec 13, 1999 | Released | Guillermo Garcia | Cincinnati Reds | — | Release |
| Dec 13, 1999 | Released | Jed Hansen | San Diego Padres | — | Release |
| Dec 13, 1999 | Released | Mendy Lopez | Kansas City Royals | — | Release |
| Dec 13, 1999 | Released | Scott McClain | Tampa Bay Devil Rays | — | Release |
| Dec 13, 1999 | Signed as free agent | Ryan McGuire | — | New York Mets | Free agent signing |
| Dec 13, 1999 | Released | Alvin Morman | Kansas City Royals | — | Release |
| Dec 13, 1999 | Signed as free agent | James Mouton | — | Milwaukee Brewers | Free agent signing |
| Dec 13, 1999 | Released | Alan Newman | Tampa Bay Devil Rays | — | Release |
| Dec 13, 1999 | Signed as free agent | Greg Vaughn | — | Tampa Bay Devil Rays | Free agent signing |
| Dec 13, 1999 | Trade | Abraham Nunez | Arizona Diamondbacks | Florida Marlins | Trade |
| Dec 13, 1999 | Trade | Jerry Spradlin | San Francisco Giants | Kansas City Royals | Trade |
| Dec 13, 1999 | Trade | Unnamed | Florida Marlins | Minnesota Twins | $ |
| Dec 13, 1999 | Trade | Johan Santana | Florida Marlins | Minnesota Twins | Trade |
| Dec 13, 1999 | Trade | Jared Camp | Minnesota Twins | Florida Marlins | Trade |
| Dec 13, 1999 | Trade | Brandon Knight | Texas Rangers | New York Yankees | Trade |
| Dec 13, 1999 | Trade | Sam Marsonek | Texas Rangers | New York Yankees | Trade |
| Dec 13, 1999 | Trade | Chad Curtis | New York Yankees | Texas Rangers | Trade |
| Dec 13, 1999 | Trade | Augie Ojeda | Baltimore Orioles | Chicago Cubs | Trade |
| Dec 13, 1999 | Trade | Richard Negrette | Chicago Cubs | Baltimore Orioles | Trade |
| Dec 13, 1999 | Trade | Rolando Arrojo | Tampa Bay Devil Rays | Colorado Rockies | Trade |
| Dec 13, 1999 | Trade | Aaron Ledesma | Tampa Bay Devil Rays | Colorado Rockies | Trade |
| Dec 13, 1999 | Trade | Vinny Castilla | Colorado Rockies | Tampa Bay Devil Rays | Trade |
| Dec 13, 1999 | Trade | Unnamed | Milwaukee Brewers | Oakland Athletics | $ |
| Dec 13, 1999 | Trade | Jeff Cirillo | Milwaukee Brewers | Colorado Rockies | Trade |
| Dec 13, 1999 | Trade | Scott Karl | Milwaukee Brewers | Colorado Rockies | Trade |
| Dec 13, 1999 | Trade | Henry Blanco | Colorado Rockies | Milwaukee Brewers | Trade |
| Dec 13, 1999 | Trade | Justin Miller | Colorado Rockies | Oakland Athletics | Trade |
| Dec 13, 1999 | Trade | Jamey Wright | Colorado Rockies | Milwaukee Brewers | Trade |
| Dec 13, 1999 | Trade | Jimmy Haynes | Oakland Athletics | Milwaukee Brewers | Trade |
| Dec 13, 1999 | Trade | Roberto Manzueta | Arizona Diamondbacks | Pittsburgh Pirates | Trade |
| Dec 13, 1999 | Trade | Brad Clontz | Pittsburgh Pirates | Arizona Diamondbacks | Trade |
| Dec 13, 1999 | Trade | Bruce Aven | Florida Marlins | Pittsburgh Pirates | Trade |
| Dec 13, 1999 | Trade | Brant Brown | Pittsburgh Pirates | Florida Marlins | Trade |
| Dec 12, 1999 | Signed as free agent | Butch Henry | — | Colorado Rockies | Free agent signing |
| Dec 12, 1999 | Signed as free agent | Rudy Seanez | — | Atlanta Braves | Free agent signing |
| Dec 12, 1999 | Trade | Manny Alexander | Chicago Cubs | Boston Red Sox | Trade |
| Dec 12, 1999 | Trade | Damon Buford | Boston Red Sox | Chicago Cubs | Trade |
| Dec 12, 1999 | Trade | Terry Adams | Chicago Cubs | Los Angeles Dodgers | Trade |
| Dec 12, 1999 | Trade | Chad Ricketts | Chicago Cubs | Los Angeles Dodgers | Trade |
| Dec 12, 1999 | Trade | Ismael Valdez | Los Angeles Dodgers | Chicago Cubs | Trade |
| Dec 12, 1999 | Trade | Eric Young | Los Angeles Dodgers | Chicago Cubs | Trade |
| Dec 12, 1999 | Trade | Bobby Estalella | Philadelphia Phillies | San Francisco Giants | Trade |
| Dec 12, 1999 | Trade | Chris Brock | San Francisco Giants | Philadelphia Phillies | Trade |
| Dec 11, 1999 | Signed as free agent | Todd Zeile | — | New York Mets | Free agent signing |
| Dec 10, 1999 | Signed as free agent | Doug Bochtler | — | Kansas City Royals | Free agent signing |
| Dec 10, 1999 | Released | Juan Melo | Cincinnati Reds | — | Release |
| Dec 10, 1999 | Signed as free agent | Dale Sveum | — | Pittsburgh Pirates | Free agent signing |
| Dec 10, 1999 | Trade | Chuck McElroy | New York Mets | Baltimore Orioles | Trade |
| Dec 10, 1999 | Trade | Jesse Orosco | Baltimore Orioles | New York Mets | Trade |
| Dec 9, 1999 | Signed as free agent | Harold Baines | — | Baltimore Orioles | Free agent signing |
| Dec 9, 1999 | Released | Edwin Diaz | Arizona Diamondbacks | — | Release |
| Dec 9, 1999 | Signed as free agent | Tom Goodwin | — | Colorado Rockies | Free agent signing |
| Dec 8, 1999 | Signed as free agent | Phil Hiatt | — | Colorado Rockies | Free agent signing |
| Dec 8, 1999 | Signed as free agent | Larry Sutton | — | St. Louis Cardinals | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Luis Alicea | — | Texas Rangers | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Jeff Brantley | — | Philadelphia Phillies | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Jacob Brumfield | — | Toronto Blue Jays | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Mike Busby | — | Milwaukee Brewers | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Brian Hunter | — | Atlanta Braves | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Michael Jackson | — | Philadelphia Phillies | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Mark Langston | — | Cleveland Indians | Free agent signing |
| Dec 7, 1999 | Released | Doug Linton | Baltimore Orioles | — | Release |
| Dec 7, 1999 | Signed as free agent | Eric Ludwick | — | Milwaukee Brewers | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Julio Manon | — | Milwaukee Brewers | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Mike Munoz | — | Texas Rangers | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Rey Sanchez | — | Kansas City Royals | Free agent signing |
| Dec 7, 1999 | Signed as free agent | Allen Watson | — | New York Yankees | Free agent signing |
| Dec 7, 1999 | Trade | Scott Randall | Colorado Rockies | Minnesota Twins | Trade |
| Dec 7, 1999 | Trade | Chris Latham | Minnesota Twins | Colorado Rockies | Trade |
| Dec 6, 1999 | Signed as free agent | Jay Buhner | — | Seattle Mariners | Free agent signing |
| Dec 6, 1999 | Released | Melvin Bunch | Seattle Mariners | — | Release |
| Dec 6, 1999 | Signed as free agent | David Cone | — | New York Yankees | Free agent signing |
| Dec 6, 1999 | Signed as free agent | Jose Herrera | — | Baltimore Orioles | Free agent signing |
| Dec 6, 1999 | Signed as free agent | Sandy Martinez | — | Florida Marlins | Free agent signing |
| Dec 4, 1999 | Signed as free agent | Howie Clark | — | Baltimore Orioles | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Brian Barber | — | Cleveland Indians | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Bryan Corey | — | Oakland Athletics | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Joe Depastino | — | Baltimore Orioles | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Doug Henry | — | Houston Astros | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Scott Kamieniecki | — | Cleveland Indians | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Mike Kelly | — | New York Mets | Free agent signing |
| Dec 3, 1999 | Signed as free agent | Russ Springer | — | Arizona Diamondbacks | Free agent signing |
| Dec 2, 1999 | Signed as free agent | Tony Eusebio | — | Houston Astros | Free agent signing |
| Dec 2, 1999 | Signed as free agent | David Weathers | — | Milwaukee Brewers | Free agent signing |
| Dec 1, 1999 | Signed as free agent | Bubba Carpenter | — | Colorado Rockies | Free agent signing |
| Dec 1, 1999 | Signed as free agent | Giovanni Carrara | — | Colorado Rockies | Free agent signing |
| Dec 1, 1999 | Released | Chili Davis | New York Yankees | — | Release |
| Dec 1, 1999 | Signed as free agent | Kevin Jarvis | — | Colorado Rockies | Free agent signing |
| Dec 1, 1999 | Signed as free agent | Matt Luke | — | Milwaukee Brewers | Free agent signing |
| Dec 1, 1999 | Signed as free agent | Norberto Martin | — | Milwaukee Brewers | Free agent signing |
| Dec 1, 1999 | Signed as free agent | Willie Morales | — | Baltimore Orioles | Free agent signing |
| Nov 30, 1999 | Signed as free agent | Robin Jennings | — | Minnesota Twins | Free agent signing |
| Nov 30, 1999 | Signed as free agent | Hector Ortiz | — | Kansas City Royals | Free agent signing |
| Nov 29, 1999 | Signed as free agent | Mike Oquist | — | Detroit Tigers | Free agent signing |
| Nov 29, 1999 | Released | J. R. Phillips | Colorado Rockies | — | Release |
| Nov 29, 1999 | Signed as free agent | Mike Stanton | — | New York Yankees | Free agent signing |
| Nov 24, 1999 | Signed as free agent | Heathcliff Slocumb | — | St. Louis Cardinals | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Will Brunson | — | Oakland Athletics | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Dave McCarty | — | Oakland Athletics | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Chad Ogea | — | Detroit Tigers | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Tommy Phelps | — | Detroit Tigers | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Rich Sauveur | — | Oakland Athletics | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Aaron Small | — | Colorado Rockies | Free agent signing |
| Nov 23, 1999 | Signed as free agent | Jeff Tam | — | Oakland Athletics | Free agent signing |
| Nov 22, 1999 | Signed as free agent | John Roskos | — | San Diego Padres | Free agent signing |
| Nov 22, 1999 | Signed as free agent | Stan Spencer | — | San Diego Padres | Free agent signing |
| Nov 22, 1999 | Signed as free agent | Todd Van Poppel | — | Chicago Cubs | Free agent signing |
| Nov 22, 1999 | Signed as free agent | Joe Vitiello | — | San Diego Padres | Free agent signing |
| Nov 22, 1999 | Signed as free agent | George Williams | — | San Diego Padres | Free agent signing |
| Nov 22, 1999 | Released | Ernie Young | Arizona Diamondbacks | — | Release |
| Nov 19, 1999 | Signed as free agent | Jason Bere | — | Milwaukee Brewers | Free agent signing |
| Nov 19, 1999 | Signed as free agent | Mike Magnante | — | Oakland Athletics | Free agent signing |
| Nov 18, 1999 | Released | Rafael Betancourt | Boston Red Sox | — | Release |
| Nov 18, 1999 | Signed as free agent | Travis Driskill | — | Houston Astros | Free agent signing |
| Nov 18, 1999 | Released | Luis Garcia | Detroit Tigers | — | Release |
| Nov 18, 1999 | Signed as free agent | Raul Gonzalez | — | Chicago Cubs | Free agent signing |
| Nov 18, 1999 | Signed as free agent | Mark Lewis | — | Cincinnati Reds | Free agent signing |
| Nov 18, 1999 | Signed as free agent | Bry Nelson | — | Arizona Diamondbacks | Free agent signing |
| Nov 18, 1999 | Signed as free agent | Brandon Puffer | — | Colorado Rockies | Free agent signing |
| Nov 18, 1999 | Released | Marino Santana | Boston Red Sox | — | Release |
| Nov 18, 1999 | Signed as free agent | Travis Smith | — | Milwaukee Brewers | Free agent signing |
| Nov 18, 1999 | Signed as free agent | Mike Trombley | — | Baltimore Orioles | Free agent signing |
| Nov 18, 1999 | Signed | Merkin Valdez | — | Atlanta Braves | Amateur free agent signing |
| Nov 18, 1999 | Released | Bob Wolcott | Boston Red Sox | — | Release |
| Nov 18, 1999 | Trade | Kelly Ramos | New York Mets | Boston Red Sox | Trade |
| Nov 17, 1999 | Signed as free agent | Rich Butler | — | Seattle Mariners | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Jerry Dipoto | — | Colorado Rockies | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Damon Hollins | — | Milwaukee Brewers | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Robert Machado | — | Seattle Mariners | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Carlos Mendez | — | Detroit Tigers | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Chad Mottola | — | Toronto Blue Jays | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Yohanny Valera | — | Montreal Expos | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Ed Vosberg | — | Colorado Rockies | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Pete Walker | — | Colorado Rockies | Free agent signing |
| Nov 17, 1999 | Signed as free agent | Jason Wood | — | Pittsburgh Pirates | Free agent signing |
| Nov 17, 1999 | Trade | Curt Leskanic | Colorado Rockies | Milwaukee Brewers | Trade |
| Nov 17, 1999 | Trade | Mike Myers | Milwaukee Brewers | Colorado Rockies | Trade |
| Nov 16, 1999 | Signed as free agent | Chris Coste | — | Cleveland Indians | Free agent signing |
| Nov 16, 1999 | Signed as free agent | Brooks Kieschnick | — | Cincinnati Reds | Free agent signing |
| Nov 16, 1999 | Signed as free agent | Larry Luebbers | — | Cincinnati Reds | Free agent signing |
| Nov 16, 1999 | Released | Mike Matheny | Toronto Blue Jays | — | Release |
| Nov 16, 1999 | Signed as free agent | Izzy Molina | — | Kansas City Royals | Free agent signing |
| Nov 16, 1999 | Signed as free agent | Bobby Munoz | — | Cincinnati Reds | Free agent signing |
| Nov 16, 1999 | Signed as free agent | Brian Shouse | — | New York Mets | Free agent signing |
| Nov 16, 1999 | Signed | Jason Stanford | — | Cleveland Indians | Amateur free agent signing |
| Nov 16, 1999 | Trade | Darryl Kile | Colorado Rockies | St. Louis Cardinals | Trade |
| Nov 16, 1999 | Trade | Luther Hackman | Colorado Rockies | St. Louis Cardinals | Trade |
| Nov 16, 1999 | Trade | Dave Veres | Colorado Rockies | St. Louis Cardinals | Trade |
| Nov 16, 1999 | Trade | Manny Aybar | St. Louis Cardinals | Colorado Rockies | Trade |
| Nov 16, 1999 | Trade | Brent Butler | St. Louis Cardinals | Colorado Rockies | Trade |
| Nov 16, 1999 | Trade | Rich Croushore | St. Louis Cardinals | Colorado Rockies | Trade |
| Nov 16, 1999 | Trade | Jose Jimenez | St. Louis Cardinals | Colorado Rockies | Trade |
| Nov 15, 1999 | Signed | William Bergolla | — | Cincinnati Reds | Amateur free agent signing |
| Nov 15, 1999 | Signed | Jerry Gil | — | Arizona Diamondbacks | Amateur free agent signing |
| Nov 15, 1999 | Signed as free agent | Mark Holzemer | — | Philadelphia Phillies | Free agent signing |
| Nov 15, 1999 | Signed as free agent | Ken Huckaby | — | Arizona Diamondbacks | Free agent signing |
| Nov 15, 1999 | Signed as free agent | Jason Maxwell | — | Minnesota Twins | Free agent signing |
| Nov 15, 1999 | Signed as free agent | Chris Petersen | — | Chicago Cubs | Free agent signing |
| Nov 15, 1999 | Signed as free agent | Luis Polonia | — | Detroit Tigers | Free agent signing |
| Nov 15, 1999 | Signed as free agent | Kelly Wunsch | — | Chicago White Sox | Free agent signing |
| Nov 15, 1999 | Trade | Brian Meadows | Florida Marlins | San Diego Padres | Trade |
| Nov 15, 1999 | Trade | Dan Miceli | San Diego Padres | Florida Marlins | Trade |
| Nov 14, 1999 | Signed as free agent | Daniel Garibay | — | Chicago Cubs | Free agent signing |
| Nov 13, 1999 | Signed as free agent | Keith Glauber | — | Cincinnati Reds | Free agent signing |
| Nov 12, 1999 | Signed as free agent | Darwin Cubillan | — | Toronto Blue Jays | Free agent signing |
| Nov 12, 1999 | Signed as free agent | Angel Guzman | — | Chicago Cubs | Free agent signing |
| Nov 12, 1999 | Signed as free agent | Geraldo Guzman | — | Arizona Diamondbacks | Free agent signing |
| Nov 12, 1999 | Signed as free agent | Marc Ronan | — | St. Louis Cardinals | Free agent signing |
| Nov 12, 1999 | Signed as free agent | Matt Skrmetta | — | Montreal Expos | Free agent signing |
| Nov 12, 1999 | Trade | Jon Nunnally | Boston Red Sox | New York Mets | Trade |
| Nov 12, 1999 | Trade | Jermaine Allensworth | New York Mets | Boston Red Sox | Trade |
| Nov 11, 1999 | Signed as free agent | Mike Gulan | — | Florida Marlins | Free agent signing |
| Nov 11, 1999 | Signed as free agent | Chris Hatcher | — | Chicago Cubs | Free agent signing |
| Nov 11, 1999 | Signed as free agent | Derrick May | — | Baltimore Orioles | Free agent signing |
| Nov 11, 1999 | Trade | Pat Hentgen | Toronto Blue Jays | St. Louis Cardinals | Trade |
| Nov 11, 1999 | Trade | Paul Spoljaric | Toronto Blue Jays | St. Louis Cardinals | Trade |
| Nov 11, 1999 | Trade | Alberto Castillo | St. Louis Cardinals | Toronto Blue Jays | Trade |
| Nov 11, 1999 | Trade | Matt DeWitt | St. Louis Cardinals | Toronto Blue Jays | Trade |
| Nov 11, 1999 | Trade | Lance Painter | St. Louis Cardinals | Toronto Blue Jays | Trade |
| Nov 10, 1999 | Signed as free agent | Jayson Durocher | — | San Diego Padres | Free agent signing |
| Nov 10, 1999 | Signed as free agent | Charlie Greene | — | Toronto Blue Jays | Free agent signing |
| Nov 10, 1999 | Trade | Adam Eaton | Philadelphia Phillies | San Diego Padres | Trade |
| Nov 10, 1999 | Trade | Carlton Loewer | Philadelphia Phillies | San Diego Padres | Trade |
| Nov 10, 1999 | Trade | Steve Montgomery | Philadelphia Phillies | San Diego Padres | Trade |
| Nov 10, 1999 | Trade | Andy Ashby | San Diego Padres | Philadelphia Phillies | Trade |
| Nov 9, 1999 | Signed as free agent | Joe Borowski | — | Cincinnati Reds | Free agent signing |
| Nov 9, 1999 | Signed as free agent | Joey Dawley | — | Atlanta Braves | Free agent signing |
| Nov 8, 1999 | Signed as free agent | Jalal Leach | — | Philadelphia Phillies | Free agent signing |
| Nov 8, 1999 | Signed as free agent | Steve Sisco | — | Atlanta Braves | Free agent signing |
| Nov 8, 1999 | Trade | Shawn Green | Toronto Blue Jays | Los Angeles Dodgers | Trade |
| Nov 8, 1999 | Trade | Jorge Nunez | Toronto Blue Jays | Los Angeles Dodgers | Trade |
| Nov 8, 1999 | Trade | Pedro Borbon | Los Angeles Dodgers | Toronto Blue Jays | Trade |
| Nov 8, 1999 | Trade | Raul Mondesi | Los Angeles Dodgers | Toronto Blue Jays | Trade |
| Nov 7, 1999 | Signed as free agent | Alan Zinter | — | Chicago Cubs | Free agent signing |
| Nov 5, 1999 | Signed | Danys Baez | — | Cleveland Indians | Amateur free agent signing |
| Nov 5, 1999 | Released | Jorge Fabregas | Atlanta Braves | — | Release |
| Nov 5, 1999 | Signed as free agent | Mike Heathcott | — | Chicago Cubs | Free agent signing |
| Nov 4, 1999 | Signed as free agent | Steve Decker | — | Anaheim Angels | Free agent signing |
| Nov 4, 1999 | Signed as free agent | Vicente Palacios | — | San Diego Padres | Free agent signing |
| Nov 4, 1999 | Signed as free agent | Jarrod Patterson | — | Pittsburgh Pirates | Free agent signing |
| Nov 4, 1999 | Signed as free agent | Neil Weber | — | Cincinnati Reds | Free agent signing |
| Nov 4, 1999 | Signed as free agent | Chad Zerbe | — | San Francisco Giants | Free agent signing |
| Nov 3, 1999 | Signed as free agent | Yovanny Lara | — | Montreal Expos | Free agent signing |
| Nov 3, 1999 | Signed as free agent | Jeff Manto | — | Colorado Rockies | Free agent signing |
| Nov 3, 1999 | Signed as free agent | Jon Ratliff | — | Oakland Athletics | Free agent signing |
| Nov 3, 1999 | Signed as free agent | Chris Sexton | — | Cincinnati Reds | Free agent signing |
| Nov 3, 1999 | Signed as free agent | Pat Watkins | — | Cincinnati Reds | Free agent signing |
| Nov 3, 1999 | Signed as free agent | Tom Wilson | — | New York Yankees | Free agent signing |
| Nov 2, 1999 | Signed as free agent | Mike Bell | — | Cincinnati Reds | Free agent signing |
| Nov 2, 1999 | Signed as free agent | P. J. Forbes | — | Philadelphia Phillies | Free agent signing |
| Nov 2, 1999 | Signed as free agent | Chris Tremie | — | Florida Marlins | Free agent signing |
| Nov 2, 1999 | Signed as free agent | Bryan Ward | — | Philadelphia Phillies | Free agent signing |
| Nov 2, 1999 | Trade | Frank Catalanotto | Detroit Tigers | Texas Rangers | Trade |
| Nov 2, 1999 | Trade | Francisco Cordero | Detroit Tigers | Texas Rangers | Trade |
| Nov 2, 1999 | Trade | Bill Haselman | Detroit Tigers | Texas Rangers | Trade |
| Nov 2, 1999 | Trade | Gabe Kapler | Detroit Tigers | Texas Rangers | Trade |
| Nov 2, 1999 | Trade | Justin Thompson | Detroit Tigers | Texas Rangers | Trade |
| Nov 2, 1999 | Trade | Alan Webb | Detroit Tigers | Texas Rangers | Trade |
| Nov 2, 1999 | Trade | Juan Gonzalez | Texas Rangers | Detroit Tigers | Trade |
| Nov 2, 1999 | Trade | Danny Patterson | Texas Rangers | Detroit Tigers | Trade |
| Nov 2, 1999 | Trade | Gregg Zaun | Texas Rangers | Detroit Tigers | Trade |
| Nov 1, 1999 | Signed as free agent | Marty Malloy | — | Detroit Tigers | Free agent signing |
| Nov 1, 1999 | Signed as free agent | Chris Pritchett | — | Philadelphia Phillies | Free agent signing |
| Oct 30, 1999 | Signed as free agent | Adam Hyzdu | — | Pittsburgh Pirates | Free agent signing |
| Oct 30, 1999 | Trade | Unnamed | Colorado Rockies | Cincinnati Reds | $ |
| Oct 30, 1999 | Trade | Dante Bichette | Colorado Rockies | Cincinnati Reds | Trade |
| Oct 30, 1999 | Trade | Stan Belinda | Cincinnati Reds | Colorado Rockies | Trade |
| Oct 30, 1999 | Trade | Jeffrey Hammonds | Cincinnati Reds | Colorado Rockies | Trade |
| Oct 29, 1999 | Signed as free agent | Felipe Crespo | — | San Francisco Giants | Free agent signing |
| Oct 29, 1999 | Signed as free agent | Ozzie Timmons | — | Tampa Bay Devil Rays | Free agent signing |
| Oct 28, 1999 | Released | Eric Gunderson | Texas Rangers | — | Release |
| Oct 28, 1999 | Signed as free agent | Oscar Henriquez | — | San Diego Padres | Free agent signing |
| Oct 28, 1999 | Signed as free agent | Terry Jones | — | Los Angeles Dodgers | Free agent signing |
| Oct 28, 1999 | Signed as free agent | Chris Seelbach | — | Atlanta Braves | Free agent signing |
| Oct 27, 1999 | Signed as free agent | Mike Mahoney | — | Chicago Cubs | Free agent signing |
| Oct 25, 1999 | Signed as free agent | Kris Foster | — | Los Angeles Dodgers | Free agent signing |
| Oct 25, 1999 | Signed as free agent | Matt Whiteside | — | San Diego Padres | Free agent signing |
| Oct 24, 1999 | Signed as free agent | Alex Prieto | — | Kansas City Royals | Free agent signing |
| Oct 22, 1999 | Signed as free agent | Mike Coolbaugh | — | New York Yankees | Free agent signing |
| Oct 21, 1999 | Signed | Devern Hansack | — | Houston Astros | Amateur free agent signing |
| Oct 20, 1999 | Released | John Hudek | Toronto Blue Jays | — | Release |
| Oct 15, 1999 | Released | Gary Gaetti | Chicago Cubs | — | Release |
| Oct 15, 1999 | Signed as free agent | Mike James | — | St. Louis Cardinals | Free agent signing |
| Oct 14, 1999 | Released | Travis Smith | Milwaukee Brewers | — | Release |
| Oct 12, 1999 | Signed as free agent | J. J. Trujillo | — | San Diego Padres | Free agent signing with first major-league team |
| Oct 11, 1999 | Released | Brian Johnson | Cincinnati Reds | — | Release |
| Oct 7, 1999 | Released | Mike Mahoney | Atlanta Braves | — | Release |
| Oct 7, 1999 | Signed | Chin-hui Tsao | — | Colorado Rockies | Amateur free agent signing |
| Oct 5, 1999 | Released | Lance Johnson | Chicago Cubs | — | Release |
| Sep 30, 1999 | Signed as free agent | Agustin Montero | — | Los Angeles Dodgers | Free agent signing |
| Sep 27, 1999 | Released | Mark Portugal | Boston Red Sox | — | Release |
| Sep 27, 1999 | Released | Jason Simontacchi | Pittsburgh Pirates | — | Release |
| Sep 22, 1999 | Trade | Adrian Myers | Texas Rangers | Seattle Mariners | Trade |
| Sep 14, 1999 | Trade | Justin Dunning | Seattle Mariners | New York Mets | Trade |
| Sep 14, 1999 | Trade | Glendon Rusch | Kansas City Royals | New York Mets | Trade |
| Sep 14, 1999 | Trade | Dan Murray | New York Mets | Kansas City Royals | Trade |
| Sep 13, 1999 | Released | Domingo Cedeno | Philadelphia Phillies | — | Release |
| Sep 13, 1999 | Trade | Jaime Goudie | Cincinnati Reds | Toronto Blue Jays | Trade |
| Sep 11, 1999 | Released | Steve Scarsone | Kansas City Royals | — | Release |
| Sep 10, 1999 | Signed as free agent | Shane Andrews | — | Chicago Cubs | Free agent signing |
| Sep 10, 1999 | Released | Doug Creek | Chicago Cubs | — | Release |
| Sep 9, 1999 | Trade | Freddy Garcia | Pittsburgh Pirates | Atlanta Braves | Trade |
| Sep 9, 1999 | Trade | Greg Dukeman | Atlanta Braves | Pittsburgh Pirates | Trade |
| Sep 7, 1999 | Released | Shane Andrews | Montreal Expos | — | Release |
| Sep 7, 1999 | Released | Mike James | Anaheim Angels | — | Release |
| Sep 5, 1999 | Signed as free agent | Sean Bergman | — | Atlanta Braves | Free agent signing |
| Sep 5, 1999 | Released | Steve Falteisek | Milwaukee Brewers | — | Release |
| Sep 3, 1999 | Signed as free agent | Bobby Ayala | — | Chicago Cubs | Free agent signing |
| Sep 3, 1999 | Trade | Juan Melo | Toronto Blue Jays | Cincinnati Reds | Trade |
| Sep 2, 1999 | Signed as free agent | Tim Unroe | — | Kansas City Royals | Free agent signing |
| Sep 1, 1999 | Signed as free agent | John Cangelosi | — | Colorado Rockies | Free agent signing |
| Sep 1, 1999 | Trade | Cole Liniak | Boston Red Sox | Chicago Cubs | Trade |
| Aug 31, 1999 | Released | Sean Bergman | Houston Astros | — | Release |
| Aug 31, 1999 | Released | Pat Borders | Cleveland Indians | — | Release |
| Aug 31, 1999 | Signed as free agent | Pat Borders | — | Toronto Blue Jays | Free agent signing |
| Aug 31, 1999 | Released | Alex Diaz | Houston Astros | — | Release |
| Aug 31, 1999 | Signed as free agent | Jorge Fabregas | — | Atlanta Braves | Free agent signing |
| Aug 31, 1999 | Released | Reggie Williams | Anaheim Angels | — | Release |
| Aug 31, 1999 | Trade | Jimmy Hamilton | Cleveland Indians | Baltimore Orioles | Trade |
| Aug 31, 1999 | Trade | Rod Beck | Chicago Cubs | Boston Red Sox | Trade |
| Aug 31, 1999 | Trade | Mark Guthrie | Boston Red Sox | Chicago Cubs | Trade |
| Aug 31, 1999 | Trade | Tyler Houston | Chicago Cubs | Cleveland Indians | Trade |
| Aug 31, 1999 | Trade | Richard Negrette | Cleveland Indians | Chicago Cubs | Trade |
| Aug 31, 1999 | Trade | Belvani Martinez | Arizona Diamondbacks | Colorado Rockies | Trade |
| Aug 31, 1999 | Trade | Lenny Harris | Colorado Rockies | Arizona Diamondbacks | Trade |
| Aug 31, 1999 | Trade | Stan Javier | San Francisco Giants | Houston Astros | Trade |
| Aug 31, 1999 | Trade | Joe Messman | Houston Astros | San Francisco Giants | Trade |
| Aug 30, 1999 | Released | Geronimo Berroa | Toronto Blue Jays | — | Release |
| Aug 30, 1999 | Signed as free agent | Don Wengert | — | Atlanta Braves | Free agent signing |
| Aug 28, 1999 | Signed as free agent | Mike Blowers | — | Seattle Mariners | Free agent signing |
| Aug 27, 1999 | Released | Bobby Ayala | Montreal Expos | — | Release |
| Aug 27, 1999 | Signed | Ronny Cedeno | — | Chicago Cubs | Amateur free agent signing |
| Aug 27, 1999 | Released | Don Wengert | New York Yankees | — | Release |
| Aug 27, 1999 | Trade | Harold Baines | Baltimore Orioles | Cleveland Indians | Trade |
| Aug 27, 1999 | Trade | Juan Aracena | Cleveland Indians | Baltimore Orioles | Trade |
| Aug 27, 1999 | Trade | Jeff Fassero | Seattle Mariners | Texas Rangers | Trade |
| Aug 26, 1999 | Signed | Manny Corpas | — | Colorado Rockies | Amateur free agent signing |
| Aug 26, 1999 | Signed as free agent | Brendan Donnelly | — | Toronto Blue Jays | Free agent signing |
| Aug 26, 1999 | Released | Jorge Fabregas | Florida Marlins | — | Release |
| Aug 26, 1999 | Signed as free agent | Jim Poole | — | Cleveland Indians | Free agent signing |
| Aug 26, 1999 | Signed as free agent | Ken Ryan | — | Pittsburgh Pirates | Free agent signing |
| Aug 26, 1999 | Trade | Jerry Amador | Seattle Mariners | Detroit Tigers | Trade |
| Aug 25, 1999 | Released | Brendan Donnelly | Pittsburgh Pirates | — | Release |
| Aug 25, 1999 | Trade | Jason Boyd | Arizona Diamondbacks | Pittsburgh Pirates | Trade |
| Aug 24, 1999 | Trade | Joey Nation | Atlanta Braves | Chicago Cubs | Trade |
| Aug 24, 1999 | Trade | Mike Matthews | Boston Red Sox | St. Louis Cardinals | Trade |
| Aug 24, 1999 | Trade | Dave Benham | Boston Red Sox | St. Louis Cardinals | Trade |
| Aug 24, 1999 | Trade | Kent Mercker | St. Louis Cardinals | Boston Red Sox | Trade |
| Aug 23, 1999 | Released | Jim Poole | Philadelphia Phillies | — | Release |
| Aug 23, 1999 | Trade | Pat Lynch | Toronto Blue Jays | Colorado Rockies | Trade |
| Aug 22, 1999 | Released | Ken Ryan | Philadelphia Phillies | — | Release |
| Aug 20, 1999 | Released | Lenny Webster | Boston Red Sox | — | Release |
| Aug 20, 1999 | Signed as free agent | Matt Whisenant | — | San Diego Padres | Free agent signing |
| Aug 20, 1999 | Trade | Carl Dale | Oakland Athletics | Milwaukee Brewers | Trade |
| Aug 19, 1999 | Released | Walt McKeel | Detroit Tigers | — | Release |
| Aug 18, 1999 | Signed as free agent | Brendan Donnelly | — | Pittsburgh Pirates | Free agent signing |
| Aug 18, 1999 | Signed as free agent | Turner Ward | — | Arizona Diamondbacks | Free agent signing |
| Aug 18, 1999 | Trade | Rich Becker | Milwaukee Brewers | Oakland Athletics | Trade |
| Aug 16, 1999 | Signed | Jose Reyes | — | New York Mets | Amateur free agent signing |
| Aug 14, 1999 | Released | Terry Mathews | Kansas City Royals | — | Release |
| Aug 14, 1999 | Released | Matt Whisenant | Kansas City Royals | — | Release |
| Aug 13, 1999 | Signed as free agent | Jeff Manto | — | Cleveland Indians | Free agent signing |
| Aug 13, 1999 | Trade | Jeremy Jackson | Kansas City Royals | New York Mets | Trade |
| Aug 13, 1999 | Trade | Derek Wallace | New York Mets | Kansas City Royals | Trade |
| Aug 12, 1999 | Signed as free agent | Jason Bere | — | Milwaukee Brewers | Free agent signing |
| Aug 12, 1999 | Released | Brendan Donnelly | Tampa Bay Devil Rays | — | Release |
| Aug 11, 1999 | Released | Turner Ward | Pittsburgh Pirates | — | Release |
| Aug 10, 1999 | Released | Jeff Manto | New York Yankees | — | Release |
| Aug 9, 1999 | Released | Jack McDowell | Anaheim Angels | — | Release |
| Aug 9, 1999 | Trade | Brian McRae | Colorado Rockies | Toronto Blue Jays | Trade |
| Aug 7, 1999 | Signed | Kevin Cash | — | Toronto Blue Jays | Amateur free agent signing |
| Aug 6, 1999 | Released | Charlie O'Brien | Anaheim Angels | — | Release |
| Aug 4, 1999 | Released | Jason Bere | Cincinnati Reds | — | Release |
| Aug 4, 1999 | Released | Julio Manon | Tampa Bay Devil Rays | — | Release |
| Aug 4, 1999 | Released | Hector Mercado | New York Mets | — | Release |
| Aug 4, 1999 | Signed as free agent | Jose Mercedes | — | New York Mets | Free agent signing |
| Aug 4, 1999 | Trade | Jose Olmeda | Boston Red Sox | Cleveland Indians | Trade |
| Aug 4, 1999 | Trade | Mike Matthews | Cleveland Indians | Boston Red Sox | Trade |
| Aug 3, 1999 | Trade | George Williams | Minnesota Twins | Houston Astros | Trade |
| Aug 3, 1999 | Trade | Josh Dimmick | Houston Astros | Minnesota Twins | Trade |
| Aug 2, 1999 | Signed | Ronald Belisario | — | Florida Marlins | Amateur free agent signing |
| Aug 2, 1999 | Released | Tom Candiotti | Cleveland Indians | — | Release |
| Jul 31, 1999 | Signed as free agent | John Hudek | — | Toronto Blue Jays | Free agent signing |
| Jul 31, 1999 | Trade | Unnamed | Baltimore Orioles | Cincinnati Reds | $ |
| Jul 31, 1999 | Trade | Juan Guzman | Baltimore Orioles | Cincinnati Reds | Trade |
| Jul 31, 1999 | Trade | B. J. Ryan | Cincinnati Reds | Baltimore Orioles | Trade |
| Jul 31, 1999 | Trade | Jacobo Sequea | Cincinnati Reds | Baltimore Orioles | Trade |
| Jul 31, 1999 | Trade | Mike Maroth | Boston Red Sox | Detroit Tigers | Trade |
| Jul 31, 1999 | Trade | Bryce Florie | Detroit Tigers | Boston Red Sox | Trade |
| Jul 31, 1999 | Trade | Mandy Romero | Boston Red Sox | New York Mets | Trade |
| Jul 31, 1999 | Trade | Kevin Appier | Kansas City Royals | Oakland Athletics | Trade |
| Jul 31, 1999 | Trade | Jeff D'Amico | Oakland Athletics | Kansas City Royals | Trade |
| Jul 31, 1999 | Trade | Brad Rigby | Oakland Athletics | Kansas City Royals | Trade |
| Jul 31, 1999 | Trade | Blake Stein | Oakland Athletics | Kansas City Royals | Trade |
| Jul 31, 1999 | Trade | Jason Isringhausen | New York Mets | Oakland Athletics | Trade |
| Jul 31, 1999 | Trade | Greg McMichael | New York Mets | Oakland Athletics | Trade |
| Jul 31, 1999 | Trade | Billy Taylor | Oakland Athletics | New York Mets | Trade |
| Jul 31, 1999 | Trade | Micah Bowie | Atlanta Braves | Chicago Cubs | Trade |
| Jul 31, 1999 | Trade | Ruben Quevedo | Atlanta Braves | Chicago Cubs | Trade |
| Jul 31, 1999 | Trade | Jose Hernandez | Chicago Cubs | Atlanta Braves | Trade |
| Jul 31, 1999 | Trade | Terry Mulholland | Chicago Cubs | Atlanta Braves | Trade |
| Jul 31, 1999 | Trade | Brandon Villafuerte | Florida Marlins | Detroit Tigers | Trade |
| Jul 31, 1999 | Trade | Mike Drumright | Detroit Tigers | Florida Marlins | Trade |
| Jul 31, 1999 | Trade | Rigo Beltran | New York Mets | Colorado Rockies | Trade |
| Jul 31, 1999 | Trade | Tom Johnson | New York Mets | Colorado Rockies | Trade |
| Jul 31, 1999 | Trade | Brian McRae | New York Mets | Colorado Rockies | Trade |
| Jul 31, 1999 | Trade | Darryl Hamilton | Colorado Rockies | New York Mets | Trade |
| Jul 31, 1999 | Trade | Chuck McElroy | Colorado Rockies | New York Mets | Trade |
| Jul 31, 1999 | Trade | Craig Paquette | New York Mets | St. Louis Cardinals | Trade |
| Jul 31, 1999 | Trade | Shawon Dunston | St. Louis Cardinals | New York Mets | Trade |
| Jul 31, 1999 | Trade | Geraldo Padua | New York Yankees | San Diego Padres | Trade |
| Jul 31, 1999 | Trade | Jim Leyritz | San Diego Padres | New York Yankees | Trade |
| Jul 30, 1999 | Released | John Hudek | Atlanta Braves | — | Release |
| Jul 30, 1999 | Signed as free agent | Jesse Levis | — | Cleveland Indians | Free agent signing |
| Jul 30, 1999 | Released | Jose Mercedes | Florida Marlins | — | Release |
| Jul 30, 1999 | Signed as free agent | Vicente Palacios | — | New York Mets | Free agent signing |
| Jul 30, 1999 | Released | Dave Stevens | Seattle Mariners | — | Release |
| Jul 30, 1999 | Trade | Will Silverthorn | Boston Red Sox | Tampa Bay Devil Rays | Trade |
| Jul 29, 1999 | Trade | Esteban Beltre | Baltimore Orioles | Chicago White Sox | Trade |
| Jul 29, 1999 | Trade | Mario Iglesias | Chicago White Sox | Baltimore Orioles | Trade |
| Jul 29, 1999 | Trade | Jeff DaVanon | Oakland Athletics | Anaheim Angels | Trade |
| Jul 29, 1999 | Trade | Nathan Haynes | Oakland Athletics | Anaheim Angels | Trade |
| Jul 29, 1999 | Trade | Elvin Nina | Oakland Athletics | Anaheim Angels | Trade |
| Jul 29, 1999 | Trade | Omar Olivares | Anaheim Angels | Oakland Athletics | Trade |
| Jul 29, 1999 | Trade | Randy Velarde | Anaheim Angels | Oakland Athletics | Trade |
| Jul 28, 1999 | Released | Jesse Levis | Tampa Bay Devil Rays | — | Release |
| Jul 28, 1999 | Signed as free agent | Lenny Webster | — | Boston Red Sox | Free agent signing |
| Jul 28, 1999 | Trade | Tom Davey | Toronto Blue Jays | Seattle Mariners | Trade |
| Jul 28, 1999 | Trade | Steve Sinclair | Toronto Blue Jays | Seattle Mariners | Trade |
| Jul 28, 1999 | Trade | David Segui | Seattle Mariners | Toronto Blue Jays | Trade |
| Jul 27, 1999 | Signed as free agent | Don Wengert | — | New York Yankees | Free agent signing |
| Jul 26, 1999 | Trade | Robert Ramsay | Boston Red Sox | Seattle Mariners | Trade |
| Jul 26, 1999 | Trade | Butch Huskey | Seattle Mariners | Boston Red Sox | Trade |
| Jul 26, 1999 | Trade | Greg Myers | San Diego Padres | Atlanta Braves | Trade |
| Jul 26, 1999 | Trade | Doug Dent | Atlanta Braves | San Diego Padres | Trade |
| Jul 25, 1999 | Signed as free agent | Jaime Cerda | — | New York Mets | Free agent signing |
| Jul 25, 1999 | Trade | Scott Aldred | Tampa Bay Devil Rays | Philadelphia Phillies | Trade |
| Jul 25, 1999 | Trade | Livan Hernandez | Florida Marlins | San Francisco Giants | Trade |
| Jul 25, 1999 | Trade | Jason Grilli | San Francisco Giants | Florida Marlins | Trade |
| Jul 25, 1999 | Trade | Nate Bump | San Francisco Giants | Florida Marlins | Trade |
| Jul 24, 1999 | Released | Steve Ontiveros | Milwaukee Brewers | — | Release |
| Jul 23, 1999 | Released | Jim Abbott | Milwaukee Brewers | — | Release |
| Jul 23, 1999 | Trade | Blake Mayo | Los Angeles Dodgers | Arizona Diamondbacks | Trade |
| Jul 23, 1999 | Trade | Terrence Long | New York Mets | Oakland Athletics | Trade |
| Jul 23, 1999 | Trade | Leo Vasquez | New York Mets | Oakland Athletics | Trade |
| Jul 23, 1999 | Trade | Kenny Rogers | Oakland Athletics | New York Mets | Trade |
| Jul 23, 1999 | Trade | Jose Guillen | Pittsburgh Pirates | Tampa Bay Devil Rays | Trade |
| Jul 23, 1999 | Trade | Jeff Sparks | Pittsburgh Pirates | Tampa Bay Devil Rays | Trade |
| Jul 23, 1999 | Trade | Joe Oliver | Tampa Bay Devil Rays | Pittsburgh Pirates | Trade |
| Jul 23, 1999 | Trade | Humberto Cota | Tampa Bay Devil Rays | Pittsburgh Pirates | Trade |
| Jul 22, 1999 | Released | Tim Unroe | Anaheim Angels | — | Release |
| Jul 22, 1999 | Trade | Todd Williams | Cincinnati Reds | Seattle Mariners | Trade |
| Jul 22, 1999 | Trade | Kerry Robinson | Seattle Mariners | Cincinnati Reds | Trade |
| Jul 21, 1999 | Signed | Tony Peña | — | Atlanta Braves | Amateur free agent signing |
| Jul 21, 1999 | Released | Lenny Webster | Baltimore Orioles | — | Release |
| Jul 21, 1999 | Trade | Alberto Reyes | Milwaukee Brewers | Baltimore Orioles | Trade |
| Jul 21, 1999 | Trade | Unnamed | Boston Red Sox | Tampa Bay Devil Rays | $ |
| Jul 21, 1999 | Trade | Julio Santana | Tampa Bay Devil Rays | Boston Red Sox | Trade |
| Jul 20, 1999 | Trade | Marty Barnett | Philadelphia Phillies | Tampa Bay Devil Rays | Trade |
| Jul 18, 1999 | Signed as free agent | Mark Thompson | — | St. Louis Cardinals | Free agent signing |
| Jul 17, 1999 | Released | Mark Thompson | Cincinnati Reds | — | Release |
| Jul 16, 1999 | Trade | Kevin Gordon | Colorado Rockies | Florida Marlins | Trade |
| Jul 16, 1999 | Trade | Rocky Coppinger | Baltimore Orioles | Milwaukee Brewers | Trade |
| Jul 15, 1999 | Released | Don Wengert | Kansas City Royals | — | Release |
| Jul 15, 1999 | Trade | Ryan Moskau | Los Angeles Dodgers | Florida Marlins | Trade |
| Jul 11, 1999 | Signed | Randy Ruiz | — | Cincinnati Reds | Amateur free agent signing |
| Jul 10, 1999 | Signed | Julio De Paula | — | Minnesota Twins | Amateur free agent signing |
| Jul 8, 1999 | Signed as free agent | Jeff Reed | — | Chicago Cubs | Free agent signing |
| Jul 8, 1999 | Trade | Isabel Giron | Toronto Blue Jays | San Diego Padres | Trade |
| Jul 8, 1999 | Trade | Juan Melo | San Diego Padres | Toronto Blue Jays | Trade |
| Jul 8, 1999 | Trade | Matt Mantei | Florida Marlins | Arizona Diamondbacks | Trade |
| Jul 8, 1999 | Trade | Vladimir Nunez | Arizona Diamondbacks | Florida Marlins | Trade |
| Jul 8, 1999 | Trade | Brad Penny | Arizona Diamondbacks | Florida Marlins | Trade |
| Jul 7, 1999 | Trade | Tarrik Brock | Colorado Rockies | Chicago Cubs | Trade |
| Jul 7, 1999 | Trade | Domingo Cedeno | Seattle Mariners | Philadelphia Phillies | Trade |
| Jul 7, 1999 | Trade | Jose Flores | Philadelphia Phillies | Seattle Mariners | Trade |
| Jul 5, 1999 | Trade | Ron Calloway | Arizona Diamondbacks | Montreal Expos | Trade |
| Jul 3, 1999 | Signed | Carlos Marmol | — | Chicago Cubs | Amateur free agent signing |
| Jul 3, 1999 | Signed | Roberto Novoa | — | Pittsburgh Pirates | Amateur free agent signing |
| Jul 3, 1999 | Signed | Pete Orr | — | Atlanta Braves | Amateur free agent signing |
| Jul 3, 1999 | Signed | Jose Reyes | — | Chicago Cubs | Amateur free agent signing |
| Jul 3, 1999 | Released | Mel Rojas | Montreal Expos | — | Release |
| Jul 3, 1999 | Signed | Davis Romero | — | Toronto Blue Jays | Amateur free agent signing |
| Jul 3, 1999 | Signed as free agent | Allen Watson | — | New York Yankees | Free agent signing |
| Jul 2, 1999 | Signed | Miguel Cabrera | — | Florida Marlins | Amateur free agent signing |
| Jul 2, 1999 | Signed as free agent | Jim Corsi | — | Baltimore Orioles | Free agent signing |
| Jul 2, 1999 | Signed | Hector Gimenez | — | Houston Astros | Amateur free agent signing |
| Jul 2, 1999 | Signed | Elizardo Ramirez | — | Philadelphia Phillies | Amateur free agent signing |
| Jul 2, 1999 | Released | Jeff Reed | Colorado Rockies | — | Release |
| Jul 2, 1999 | Signed | Alfredo Simon | — | Philadelphia Phillies | Amateur free agent signing |
| Jul 1, 1999 | Released | Joey Eischen | Arizona Diamondbacks | — | Release |
| Jul 1, 1999 | Signed as free agent | Dave Hollins | — | Chicago White Sox | Free agent signing |
| Jul 1, 1999 | Signed as free agent | Dave Stevens | — | Seattle Mariners | Free agent signing |
| Jun 30, 1999 | Signed as free agent | Jose Mercedes | — | Florida Marlins | Free agent signing |
| Jun 30, 1999 | Signed | Sendy Rleal | — | Baltimore Orioles | Amateur free agent signing |
| Jun 29, 1999 | Signed as free agent | Tom Candiotti | — | Cleveland Indians | Free agent signing |
| Jun 28, 1999 | Released | Allen Watson | Seattle Mariners | — | Release |
| Jun 27, 1999 | Trade | Josh Santos | San Francisco Giants | Cleveland Indians | Trade |
| Jun 27, 1999 | Trade | Andy Van Hekken | Seattle Mariners | Detroit Tigers | Trade |
| Jun 26, 1999 | Signed as free agent | Rusty Meacham | — | Houston Astros | Free agent signing |
| Jun 24, 1999 | Released | Jose Mercedes | San Diego Padres | — | Release |
| Jun 23, 1999 | Signed as free agent | Chris Michalak | — | Arizona Diamondbacks | Free agent signing |
| Jun 23, 1999 | Signed as free agent | Jim Morris | — | Tampa Bay Devil Rays | Free agent signing |
| Jun 22, 1999 | Released | Jim Corsi | Boston Red Sox | — | Release |
| Jun 21, 1999 | Released | Dave Hollins | Toronto Blue Jays | — | Release |
| Jun 21, 1999 | Released | Dave Stevens | Cleveland Indians | — | Release |
| Jun 20, 1999 | Released | Tommy Phelps | Montreal Expos | — | Release |
| Jun 19, 1999 | Signed | Hung-Chih Kuo | — | Los Angeles Dodgers | Amateur free agent signing |
| Jun 19, 1999 | Released | Chris Michalak | Anaheim Angels | — | Release |
| Jun 19, 1999 | Trade | Matt Mieske | Seattle Mariners | Houston Astros | Trade |
| Jun 19, 1999 | Trade | Kevin Hodges | Houston Astros | Seattle Mariners | Trade |
| Jun 18, 1999 | Trade | Jose Cepeda | Kansas City Royals | Atlanta Braves | Trade |
| Jun 18, 1999 | Trade | Marc Pisciotta | Atlanta Braves | Kansas City Royals | Trade |
| Jun 18, 1999 | Trade | Unnamed | New York Mets | Seattle Mariners | $ |
| Jun 18, 1999 | Trade | Mac Suzuki | Seattle Mariners | New York Mets | Trade |
| Jun 18, 1999 | Trade | Allen Watson | New York Mets | Seattle Mariners | Trade |
| Jun 16, 1999 | Released | Tom Candiotti | Oakland Athletics | — | Release |
| Jun 15, 1999 | Trade | Craig Counsell | Florida Marlins | Los Angeles Dodgers | Trade |
| Jun 12, 1999 | Trade | Dan Plesac | Toronto Blue Jays | Arizona Diamondbacks | Trade |
| Jun 12, 1999 | Trade | Tony Batista | Arizona Diamondbacks | Toronto Blue Jays | Trade |
| Jun 12, 1999 | Trade | John Frascatore | Arizona Diamondbacks | Toronto Blue Jays | Trade |
| Jun 11, 1999 | Trade | Matt Targac | Atlanta Braves | Florida Marlins | Trade |
| Jun 10, 1999 | Signed as free agent | Pat Lennon | — | Detroit Tigers | Free agent signing |
| Jun 10, 1999 | Signed as free agent | Ed Vosberg | — | Arizona Diamondbacks | Free agent signing |
| Jun 10, 1999 | Trade | Scott Chiasson | Kansas City Royals | Oakland Athletics | Trade |
| Jun 9, 1999 | Released | Pat Kelly | Toronto Blue Jays | — | Release |
| Jun 9, 1999 | Released | Pat Lennon | Toronto Blue Jays | — | Release |
| Jun 9, 1999 | Signed as free agent | John Wehner | — | Pittsburgh Pirates | Free agent signing |
| Jun 6, 1999 | Signed as free agent | Carlos Baerga | — | San Diego Padres | Free agent signing |
| Jun 5, 1999 | Released | Ed Vosberg | San Diego Padres | — | Release |
| Jun 4, 1999 | Released | Carlos Baerga | Cincinnati Reds | — | Release |
| Jun 4, 1999 | Released | Rusty Meacham | Cincinnati Reds | — | Release |
| Jun 3, 1999 | Signed as free agent | Tony Fiore | — | Minnesota Twins | Free agent signing |
| Jun 3, 1999 | Signed as free agent | Derrick May | — | Baltimore Orioles | Free agent signing |
| Jun 1, 1999 | Trade | Lyle Mouton | Baltimore Orioles | Milwaukee Brewers | Trade |
| Jun 1, 1999 | Trade | Todd Dunn | Milwaukee Brewers | Baltimore Orioles | Trade |
| May 31, 1999 | Trade | Brian Partenheimer | Boston Red Sox | Florida Marlins | Trade |
| May 31, 1999 | Trade | Rob Stanifer | Florida Marlins | Boston Red Sox | Trade |
| May 31, 1999 | Trade | John Pachot | Montreal Expos | Arizona Diamondbacks | Trade |
| May 27, 1999 | Signed as free agent | Aaron Small | — | Tampa Bay Devil Rays | Free agent signing |
| May 27, 1999 | Signed | Willy Taveras | — | Cleveland Indians | Amateur free agent signing |
| May 24, 1999 | Signed as free agent | Steve Ontiveros | — | Milwaukee Brewers | Free agent signing |
| May 23, 1999 | Released | Aaron Small | Milwaukee Brewers | — | Release |
| May 23, 1999 | Trade | Neil Weber | Arizona Diamondbacks | Los Angeles Dodgers | Trade |
| May 22, 1999 | Signed | Juan Lara | — | Cleveland Indians | Amateur free agent signing |
| May 21, 1999 | Signed | Adam Bernero | — | Detroit Tigers | Amateur free agent signing |
| May 21, 1999 | Signed as free agent | Robert Machado | — | Montreal Expos | Free agent signing |
| May 21, 1999 | Trade | Rick Aguilera | Minnesota Twins | Chicago Cubs | Trade |
| May 21, 1999 | Trade | Scott Downs | Minnesota Twins | Chicago Cubs | Trade |
| May 21, 1999 | Trade | Kyle Lohse | Chicago Cubs | Minnesota Twins | Trade |
| May 21, 1999 | Trade | Jason Ryan | Chicago Cubs | Minnesota Twins | Trade |
| May 20, 1999 | Signed | Francisco Cruceta | — | Los Angeles Dodgers | Amateur free agent signing |
| May 19, 1999 | Released | Tony Fiore | Philadelphia Phillies | — | Release |
| May 19, 1999 | Released | Robert Machado | Chicago White Sox | — | Release |
| May 17, 1999 | Signed as free agent | Mel Rojas | — | Montreal Expos | Free agent signing |
| May 17, 1999 | Signed as free agent | Dale Sveum | — | Pittsburgh Pirates | Free agent signing |
| May 15, 1999 | Signed as free agent | Heathcliff Slocumb | — | St. Louis Cardinals | Free agent signing |
| May 14, 1999 | Signed as free agent | Midre Cummings | — | Minnesota Twins | Free agent signing |
| May 12, 1999 | Released | Mel Rojas | Detroit Tigers | — | Release |
| May 11, 1999 | Signed | Fernando Nieve | — | Houston Astros | Amateur free agent signing |
| May 10, 1999 | Signed as free agent | Mark Holzemer | — | Colorado Rockies | Free agent signing |
| May 10, 1999 | Signed as free agent | Adam Hyzdu | — | Pittsburgh Pirates | Free agent signing |
| May 9, 1999 | Released | Dale Sveum | Arizona Diamondbacks | — | Release |
| May 5, 1999 | Trade | Robert Person | Toronto Blue Jays | Philadelphia Phillies | Trade |
| May 5, 1999 | Trade | Paul Spoljaric | Philadelphia Phillies | Toronto Blue Jays | Trade |
| Apr 30, 1999 | Signed as free agent | Johnny Ruffin | — | Los Angeles Dodgers | Free agent signing |
| Apr 30, 1999 | Released | Heathcliff Slocumb | Baltimore Orioles | — | Release |
| Apr 29, 1999 | Signed as free agent | Hideo Nomo | — | Milwaukee Brewers | Free agent signing |
| Apr 28, 1999 | Signed | Omar Infante | — | Detroit Tigers | Amateur free agent signing |
| Apr 28, 1999 | Trade | Brian Hunter | Detroit Tigers | Seattle Mariners | Trade |
| Apr 27, 1999 | Signed as free agent | Felipe Crespo | — | San Francisco Giants | Free agent signing |
| Apr 24, 1999 | Signed as free agent | Mike Maddux | — | Los Angeles Dodgers | Free agent signing |
| Apr 23, 1999 | Released | Hideo Nomo | Chicago Cubs | — | Release |
| Apr 22, 1999 | Trade | Bolivar Volquez | Baltimore Orioles | Tampa Bay Devil Rays | Trade |
| Apr 22, 1999 | Trade | Jerry Spradlin | Cleveland Indians | San Francisco Giants | Trade |
| Apr 22, 1999 | Trade | Dan McKinley | San Francisco Giants | Cleveland Indians | Trade |
| Apr 20, 1999 | Signed as free agent | Frank Castillo | — | Pittsburgh Pirates | Free agent signing |
| Apr 19, 1999 | Signed as free agent | Dave Silvestri | — | Anaheim Angels | Free agent signing |
| Apr 18, 1999 | Signed as free agent | Pedro Valdes | — | Texas Rangers | Free agent signing |
| Apr 16, 1999 | Trade | Unnamed | Atlanta Braves | Cincinnati Reds | $ |
| Apr 16, 1999 | Trade | John Hudek | Cincinnati Reds | Atlanta Braves | Trade |
| Apr 16, 1999 | Trade | Mark Wohlers | Atlanta Braves | Cincinnati Reds | Trade |
| Apr 16, 1999 | Trade | Robinson Checo | Detroit Tigers | Los Angeles Dodgers | Trade |
| Apr 16, 1999 | Trade | Apostol Garcia | Detroit Tigers | Los Angeles Dodgers | Trade |
| Apr 16, 1999 | Trade | Richard Roberts | Detroit Tigers | Los Angeles Dodgers | Trade |
| Apr 16, 1999 | Trade | Dave Mlicki | Los Angeles Dodgers | Detroit Tigers | Trade |
| Apr 16, 1999 | Trade | Mel Rojas | Los Angeles Dodgers | Detroit Tigers | Trade |
| Apr 15, 1999 | Signed as free agent | Pat Kelly | — | Toronto Blue Jays | Free agent signing |
| Apr 15, 1999 | Released | Mike Maddux | Montreal Expos | — | Release |
| Apr 14, 1999 | Signed | Jhonny Peralta | — | Cleveland Indians | Amateur free agent signing |
| Apr 12, 1999 | Signed as free agent | Aaron Small | — | Milwaukee Brewers | Free agent signing |
| Apr 11, 1999 | Signed as free agent | Domingo Cedeno | — | Seattle Mariners | Free agent signing |
| Apr 11, 1999 | Signed as free agent | Joe Horgan | — | San Francisco Giants | Free agent signing |
| Apr 10, 1999 | Signed as free agent | Walt McKeel | — | Detroit Tigers | Free agent signing |
| Apr 9, 1999 | Signed as free agent | Reid Cornelius | — | Florida Marlins | Free agent signing |
| Apr 9, 1999 | Signed as free agent | Tony Graffanino | — | Tampa Bay Devil Rays | Free agent signing |
| Apr 9, 1999 | Released | Dave Silvestri | Tampa Bay Devil Rays | — | Release |
| Apr 9, 1999 | Signed as free agent | Chuck Smith | — | Texas Rangers | Free agent signing |
| Apr 8, 1999 | Signed as free agent | Danny Bautista | — | Florida Marlins | Free agent signing |
| Apr 8, 1999 | Signed as free agent | Tarrik Brock | — | Colorado Rockies | Free agent signing |
| Apr 8, 1999 | Released | Domingo Cedeno | Oakland Athletics | — | Release |
| Apr 8, 1999 | Signed as free agent | Brad Clontz | — | Pittsburgh Pirates | Free agent signing |
| Apr 8, 1999 | Released | Derrick May | Montreal Expos | — | Release |
| Apr 7, 1999 | Signed as free agent | Greg Hansell | — | Pittsburgh Pirates | Free agent signing |
| Apr 7, 1999 | Released | Pat Kelly | St. Louis Cardinals | — | Release |
| Apr 6, 1999 | Released | Brad Clontz | Boston Red Sox | — | Release |
| Apr 6, 1999 | Signed as free agent | Gus Gandarillas | — | Minnesota Twins | Free agent signing |
| Apr 6, 1999 | Signed as free agent | Chris Haney | — | Cleveland Indians | Free agent signing |
| Apr 5, 1999 | Released | Chris Coste | Pittsburgh Pirates | — | Release |
| Apr 5, 1999 | Signed as free agent | Rich DeLucia | — | Cleveland Indians | Free agent signing |
| Apr 5, 1999 | Released | Gus Gandarillas | Pittsburgh Pirates | — | Release |
| Apr 5, 1999 | Signed as free agent | Chris Jones | — | Toronto Blue Jays | Free agent signing |
| Apr 5, 1999 | Signed as free agent | Adam Melhuse | — | Toronto Blue Jays | Free agent signing |
| Apr 5, 1999 | Signed as free agent | James Mouton | — | Montreal Expos | Free agent signing |
| Apr 5, 1999 | Released | Jason Pearson | Florida Marlins | — | Release |
| Apr 5, 1999 | Signed as free agent | Wily Mo Peña | — | New York Yankees | Free agent signing |
| Apr 5, 1999 | Signed as free agent | Darryl Strawberry | — | New York Yankees | Free agent signing |
| Apr 5, 1999 | Released | Pedro Valdes | Boston Red Sox | — | Release |
| Apr 5, 1999 | Signed as free agent | Ron Villone | — | Cincinnati Reds | Free agent signing |
| Apr 4, 1999 | Signed as free agent | Mark Langston | — | Cleveland Indians | Free agent signing |
| Apr 3, 1999 | Released | Brendan Donnelly | Cincinnati Reds | — | Release |
| Apr 3, 1999 | Signed as free agent | Tony Fossas | — | New York Yankees | Free agent signing |
| Apr 3, 1999 | Trade | Jason Turman | Montreal Expos | Seattle Mariners | Trade |
| Apr 3, 1999 | Trade | Bobby Ayala | Seattle Mariners | Montreal Expos | Trade |
| Apr 2, 1999 | Released | Danny Bautista | Atlanta Braves | — | Release |
| Apr 2, 1999 | Released | Tony Graffanino | Atlanta Braves | — | Release |
| Apr 2, 1999 | Released | Greg Hansell | San Francisco Giants | — | Release |
| Apr 2, 1999 | Signed as free agent | Mike Kelly | — | Colorado Rockies | Free agent signing |
| Apr 2, 1999 | Released | Adam Melhuse | Toronto Blue Jays | — | Release |
| Apr 2, 1999 | Signed as free agent | Hideo Nomo | — | Chicago Cubs | Free agent signing |
| Apr 2, 1999 | Signed as free agent | Marc Pisciotta | — | Atlanta Braves | Free agent signing |
| Apr 2, 1999 | Released | Chuck Smith | Colorado Rockies | — | Release |
| Apr 2, 1999 | Released | Ron Villone | Cleveland Indians | — | Release |
| Apr 2, 1999 | Trade | Jeff Conine | Kansas City Royals | Baltimore Orioles | Trade |
| Apr 2, 1999 | Trade | Chris Fussell | Baltimore Orioles | Kansas City Royals | Trade |
| Apr 1, 1999 | Signed as free agent | Doug Bochtler | — | Toronto Blue Jays | Free agent signing |
| Apr 1, 1999 | Released | Tony Fossas | New York Yankees | — | Release |
| Apr 1, 1999 | Signed as free agent | Alejandro Freire | — | Detroit Tigers | Free agent signing |
| Apr 1, 1999 | Released | Chris Haney | Los Angeles Dodgers | — | Release |
| Apr 1, 1999 | Released | Walt McKeel | Toronto Blue Jays | — | Release |
| Apr 1, 1999 | Trade | Justin Speier | Florida Marlins | Atlanta Braves | Trade |
| Mar 31, 1999 | Released | Jim Bruske | New York Yankees | — | Release |
| Mar 31, 1999 | Released | Elmer Dessens | Pittsburgh Pirates | — | Release |
| Mar 31, 1999 | Released | Mark Holzemer | Oakland Athletics | — | Release |
| Mar 31, 1999 | Released | Mike Kelly | Tampa Bay Devil Rays | — | Release |
| Mar 31, 1999 | Released | Mark Langston | San Diego Padres | — | Release |
| Mar 31, 1999 | Released | Steve Ontiveros | Tampa Bay Devil Rays | — | Release |
| Mar 30, 1999 | Signed as free agent | Rafael Bournigal | — | Texas Rangers | Free agent signing |
| Mar 30, 1999 | Released | John Cangelosi | Chicago White Sox | — | Release |
| Mar 30, 1999 | Released | Midre Cummings | Boston Red Sox | — | Release |
| Mar 30, 1999 | Released | Rich DeLucia | Anaheim Angels | — | Release |
| Mar 30, 1999 | Released | Marc Pisciotta | Chicago Cubs | — | Release |
| Mar 30, 1999 | Released | Aaron Small | Arizona Diamondbacks | — | Release |
| Mar 30, 1999 | Trade | Unnamed | New York Yankees | Arizona Diamondbacks | $ |
| Mar 30, 1999 | Trade | Darren Holmes | New York Yankees | Arizona Diamondbacks | Trade |
| Mar 30, 1999 | Trade | Ben Ford | Arizona Diamondbacks | New York Yankees | Trade |
| Mar 30, 1999 | Trade | Izzy Molina | Arizona Diamondbacks | New York Yankees | Trade |
| Mar 30, 1999 | Trade | Unnamed | Kansas City Royals | Oakland Athletics | $ |
| Mar 30, 1999 | Trade | Jay Witasick | Oakland Athletics | Kansas City Royals | Trade |
| Mar 30, 1999 | Trade | Unnamed | Anaheim Angels | Toronto Blue Jays | $ |
| Mar 30, 1999 | Trade | Tomas Perez | Toronto Blue Jays | Anaheim Angels | Trade |
| Mar 30, 1999 | Trade | Dave Hollins | Anaheim Angels | Toronto Blue Jays | Trade |
| Mar 30, 1999 | Trade | Clint Sodowsky | Arizona Diamondbacks | St. Louis Cardinals | Trade |
| Mar 30, 1999 | Trade | John Frascatore | St. Louis Cardinals | Arizona Diamondbacks | Trade |
| Mar 29, 1999 | Signed as free agent | D. J. Carrasco | — | Pittsburgh Pirates | Free agent signing |
| Mar 29, 1999 | Released | Chris Jones | San Diego Padres | — | Release |
| Mar 29, 1999 | Released | Joe Roa | Kansas City Royals | — | Release |
| Mar 29, 1999 | Released | Oscar Robles | Houston Astros | — | Release |
| Mar 29, 1999 | Trade | Jason Johnson | Tampa Bay Devil Rays | Baltimore Orioles | Trade |
| Mar 29, 1999 | Trade | Danny Clyburn | Baltimore Orioles | Tampa Bay Devil Rays | Trade |
| Mar 29, 1999 | Trade | Pat Watkins | Florida Marlins | Colorado Rockies | Trade |
| Mar 29, 1999 | Trade | Phil Nevin | Anaheim Angels | San Diego Padres | Trade |
| Mar 29, 1999 | Trade | Keith Volkman | Anaheim Angels | San Diego Padres | Trade |
| Mar 29, 1999 | Trade | Andy Sheets | San Diego Padres | Anaheim Angels | Trade |
| Mar 29, 1999 | Trade | Gus Kennedy | San Diego Padres | Anaheim Angels | Trade |
| Mar 28, 1999 | Released | Alberto Castillo | Chicago White Sox | — | Release |
| Mar 28, 1999 | Trade | John Cotton | Chicago Cubs | Colorado Rockies | Trade |
| Mar 28, 1999 | Trade | Kevin Rawitzer | Chicago Cubs | Colorado Rockies | Trade |
| Mar 27, 1999 | Released | Rafael Bournigal | Pittsburgh Pirates | — | Release |
| Mar 27, 1999 | Signed as free agent | Cameron Cairncross | — | Cleveland Indians | Free agent signing |
| Mar 27, 1999 | Released | Frank Castillo | Arizona Diamondbacks | — | Release |
| Mar 27, 1999 | Released | Johnny Ruffin | Kansas City Royals | — | Release |
| Mar 26, 1999 | Released | Hideo Nomo | New York Mets | — | Release |
| Mar 26, 1999 | Signed as free agent | Tony Tarasco | — | New York Yankees | Free agent signing |
| Mar 26, 1999 | Trade | Tim Laker | Los Angeles Dodgers | Pittsburgh Pirates | Trade |
| Mar 25, 1999 | Signed as free agent | Tony Fossas | — | New York Yankees | Free agent signing |
| Mar 25, 1999 | Released | Orel Hershiser | Cleveland Indians | — | Release |
| Mar 25, 1999 | Signed as free agent | Orel Hershiser | — | New York Mets | Free agent signing |
| Mar 25, 1999 | Trade | Pat Flury | Boston Red Sox | Cincinnati Reds | Trade |
| Mar 25, 1999 | Trade | Jon Nunnally | Cincinnati Reds | Boston Red Sox | Trade |
| Mar 25, 1999 | Trade | Jake Meyer | Chicago White Sox | Cincinnati Reds | Trade |
| Mar 25, 1999 | Trade | Brook Fordyce | Cincinnati Reds | Chicago White Sox | Trade |
| Mar 24, 1999 | Released | Tony Fossas | Texas Rangers | — | Release |
| Mar 23, 1999 | Signed as free agent | Carlos Baerga | — | Cincinnati Reds | Free agent signing |
| Mar 23, 1999 | Signed as free agent | Keith Glauber | — | Cincinnati Reds | Free agent signing |
| Mar 23, 1999 | Released | Joe Horgan | Cleveland Indians | — | Release |
| Mar 23, 1999 | Trade | Shane Halter | Kansas City Royals | New York Mets | Trade |
| Mar 23, 1999 | Trade | Jonathan Guzman | New York Mets | Kansas City Royals | Trade |
| Mar 21, 1999 | Released | Vicente Palacios | Toronto Blue Jays | — | Release |
| Mar 20, 1999 | Released | Reid Cornelius | Anaheim Angels | — | Release |
| Mar 20, 1999 | Signed as free agent | Guillermo Mota | — | Montreal Expos | Free agent signing |
| Mar 19, 1999 | Signed as free agent | Clemente Alvarez | — | Philadelphia Phillies | Free agent signing |
| Mar 19, 1999 | Released | Alejandro Freire | Detroit Tigers | — | Release |
| Mar 19, 1999 | Signed as free agent | Jose Mercedes | — | San Diego Padres | Free agent signing |
| Mar 18, 1999 | Signed as free agent | Joey Eischen | — | Arizona Diamondbacks | Free agent signing |
| Mar 18, 1999 | Released | Tony Tarasco | Kansas City Royals | — | Release |
| Mar 17, 1999 | Released | Carlos Baerga | St. Louis Cardinals | — | Release |
| Mar 17, 1999 | Released | Felipe Crespo | Toronto Blue Jays | — | Release |
| Mar 17, 1999 | Signed as free agent | Allen McDill | — | Texas Rangers | Free agent signing |
| Mar 15, 1999 | Signed | Daniel Cabrera | — | Baltimore Orioles | Amateur free agent signing |
| Mar 15, 1999 | Signed as free agent | Brendan Donnelly | — | Cincinnati Reds | Free agent signing |
| Mar 14, 1999 | Signed as free agent | Norberto Martin | — | Toronto Blue Jays | Free agent signing |
| Mar 12, 1999 | Released | Allen McDill | Kansas City Royals | — | Release |
| Mar 12, 1999 | Signed as free agent | Ozzie Timmons | — | Seattle Mariners | Free agent signing |
| Mar 11, 1999 | Released | Joey Eischen | Cincinnati Reds | — | Release |
| Mar 11, 1999 | Signed as free agent | Ramon Martinez | — | Boston Red Sox | Free agent signing |
| Mar 11, 1999 | Signed | Eddy Rodriguez | — | Baltimore Orioles | Amateur free agent signing |
| Mar 6, 1999 | Signed as free agent | Jim Bullinger | — | Los Angeles Dodgers | Free agent signing |
| Mar 6, 1999 | Signed as free agent | Rick Wilkins | — | Los Angeles Dodgers | Free agent signing |
| Mar 5, 1999 | Signed as free agent | Jacob Brumfield | — | Los Angeles Dodgers | Free agent signing |
| Mar 4, 1999 | Signed | Hee-Seop Choi | — | Chicago Cubs | Amateur free agent signing |
| Mar 4, 1999 | Signed | Angel Guzman | — | Kansas City Royals | Amateur free agent signing |
| Mar 4, 1999 | Signed | Oliver Perez | — | San Diego Padres | Amateur free agent signing |
| Mar 4, 1999 | Released | Curtis Pride | Kansas City Royals | — | Release |
| Mar 4, 1999 | Signed as free agent | Chad Zerbe | — | San Francisco Giants | Free agent signing |
| Mar 2, 1999 | Signed | Chris Snelling | — | Seattle Mariners | Amateur free agent signing |
| Mar 1, 1999 | Signed as free agent | Johnny Ruffin | — | Kansas City Royals | Free agent signing |
| Mar 1, 1999 | Signed as free agent | B. J. Waszgis | — | New York Yankees | Free agent signing |
| Feb 28, 1999 | Signed as free agent | Rich Garces | — | Boston Red Sox | Free agent signing |
| Feb 28, 1999 | Signed as free agent | Pat Lennon | — | Toronto Blue Jays | Free agent signing |
| Feb 26, 1999 | Signed as free agent | Pat Borders | — | Cleveland Indians | Free agent signing |
| Feb 25, 1999 | Signed as free agent | Joel Peralta | — | Anaheim Angels | Free agent signing |
| Feb 25, 1999 | Trade | Tony Womack | Pittsburgh Pirates | Arizona Diamondbacks | Trade |
| Feb 25, 1999 | Trade | Paul Weichard | Arizona Diamondbacks | Pittsburgh Pirates | Trade |
| Feb 24, 1999 | Signed as free agent | Curtis Pride | — | Kansas City Royals | Free agent signing |
| Feb 23, 1999 | Signed as free agent | Brian Hunter | — | Atlanta Braves | Free agent signing |
| Feb 23, 1999 | Signed as free agent | Joe Strong | — | Tampa Bay Devil Rays | Free agent signing |
| Feb 20, 1999 | Signed as free agent | Orel Hershiser | — | Cleveland Indians | Free agent signing |
| Feb 20, 1999 | Signed as free agent | Pat Meares | — | Pittsburgh Pirates | Free agent signing |
| Feb 19, 1999 | Signed as free agent | Julio Franco | — | Tampa Bay Devil Rays | Free agent signing |
| Feb 19, 1999 | Signed | Byung-Hyun Kim | — | Arizona Diamondbacks | Amateur free agent signing |
| Feb 18, 1999 | Signed as free agent | Dale Sveum | — | Arizona Diamondbacks | Free agent signing |
| Feb 18, 1999 | Trade | Homer Bush | New York Yankees | Toronto Blue Jays | Trade |
| Feb 18, 1999 | Trade | Graeme Lloyd | New York Yankees | Toronto Blue Jays | Trade |
| Feb 18, 1999 | Trade | David Wells | New York Yankees | Toronto Blue Jays | Trade |
| Feb 18, 1999 | Trade | Roger Clemens | Toronto Blue Jays | New York Yankees | Trade |
| Feb 17, 1999 | Signed as free agent | John Jaha | — | Oakland Athletics | Free agent signing |
| Feb 16, 1999 | Signed as free agent | Alberto Castillo | — | Chicago White Sox | Free agent signing |
| Feb 16, 1999 | Signed as free agent | Robinson Checo | — | Detroit Tigers | Free agent signing |
| Feb 16, 1999 | Signed as free agent | Shawon Dunston | — | St. Louis Cardinals | Free agent signing |
| Feb 16, 1999 | Signed | Bobby Kielty | — | Minnesota Twins | Amateur free agent signing |
| Feb 16, 1999 | Signed as free agent | Eduardo Perez | — | St. Louis Cardinals | Free agent signing |
| Feb 10, 1999 | Signed as free agent | Orlando Merced | — | Montreal Expos | Free agent signing |
| Feb 9, 1999 | Signed as free agent | Rick Greene | — | Cincinnati Reds | Free agent signing |
| Feb 9, 1999 | Released | Pat Lennon | Toronto Blue Jays | — | Release |
| Feb 9, 1999 | Trade | John Ambrose | Chicago White Sox | St. Louis Cardinals | Trade |
| Feb 9, 1999 | Trade | Sean Lowe | St. Louis Cardinals | Chicago White Sox | Trade |
| Feb 8, 1999 | Signed as free agent | Pete Walker | — | Colorado Rockies | Free agent signing |
| Feb 5, 1999 | Signed as free agent | Jeff Juden | — | New York Yankees | Free agent signing |
| Feb 5, 1999 | Signed as free agent | Calvin Maduro | — | Baltimore Orioles | Free agent signing |
| Feb 4, 1999 | Signed as free agent | Mike Fetters | — | Baltimore Orioles | Free agent signing |
| Feb 4, 1999 | Signed as free agent | Chad Fonville | — | Boston Red Sox | Free agent signing |
| Feb 4, 1999 | Signed as free agent | Carlos Reyes | — | San Diego Padres | Free agent signing |
| Feb 4, 1999 | Trade | Ralph Milliard | New York Mets | Cincinnati Reds | Trade |
| Feb 4, 1999 | Trade | Mark Corey | Cincinnati Reds | New York Mets | Trade |
| Feb 3, 1999 | Signed as free agent | Esteban Beltre | — | Baltimore Orioles | Free agent signing |
| Feb 3, 1999 | Signed as free agent | Jamie Brewington | — | Cleveland Indians | Free agent signing |
| Feb 3, 1999 | Signed as free agent | Wil Cordero | — | Cleveland Indians | Free agent signing |
| Feb 3, 1999 | Signed as free agent | Joe Oliver | — | Tampa Bay Devil Rays | Free agent signing |
| Feb 3, 1999 | Signed as free agent | Bill Selby | — | Cleveland Indians | Free agent signing |
| Feb 3, 1999 | Signed as free agent | Paul Wagner | — | Cleveland Indians | Free agent signing |
| Feb 3, 1999 | Signed as free agent | Tim Young | — | Boston Red Sox | Free agent signing |
| Feb 2, 1999 | Signed as free agent | Shawn Gilbert | — | Los Angeles Dodgers | Free agent signing |
| Feb 2, 1999 | Signed as free agent | Joe Grahe | — | Philadelphia Phillies | Free agent signing |
| Feb 2, 1999 | Signed | Hector Luna | — | Cleveland Indians | Amateur free agent signing |
| Feb 2, 1999 | Signed as free agent | Mike Maddux | — | Montreal Expos | Free agent signing |
| Feb 2, 1999 | Signed as free agent | Rusty Meacham | — | Cincinnati Reds | Free agent signing |
| Feb 2, 1999 | Signed as free agent | Melvin Mora | — | New York Mets | Free agent signing |
| Feb 2, 1999 | Signed | Beltran Perez | — | Arizona Diamondbacks | Amateur free agent signing |
| Feb 2, 1999 | Trade | Mark Sweeney | San Diego Padres | Cincinnati Reds | Trade |
| Feb 2, 1999 | Trade | Greg Vaughn | San Diego Padres | Cincinnati Reds | Trade |
| Feb 2, 1999 | Trade | Damian Jackson | Cincinnati Reds | San Diego Padres | Trade |
| Feb 2, 1999 | Trade | Reggie Sanders | Cincinnati Reds | San Diego Padres | Trade |
| Feb 2, 1999 | Trade | Josh Harris | Cincinnati Reds | San Diego Padres | Trade |
| Feb 1, 1999 | Signed as free agent | Chris Jones | — | San Diego Padres | Free agent signing |
| Feb 1, 1999 | Trade | Mike Lowell | New York Yankees | Florida Marlins | Trade |
| Feb 1, 1999 | Trade | Mark Johnson | Florida Marlins | New York Yankees | Trade |
| Feb 1, 1999 | Trade | Todd Noel | Florida Marlins | New York Yankees | Trade |
| Feb 1, 1999 | Trade | Ed Yarnall | Florida Marlins | New York Yankees | Trade |
| Jan 31, 1999 | Signed | Renyel Pinto | — | Chicago Cubs | Amateur free agent signing |
| Jan 29, 1999 | Signed as free agent | Doug Creek | — | Chicago Cubs | Free agent signing |
| Jan 29, 1999 | Signed as free agent | Dennis Springer | — | Florida Marlins | Free agent signing |
| Jan 28, 1999 | Signed as free agent | Jamie Walker | — | Kansas City Royals | Free agent signing |
| Jan 27, 1999 | Signed as free agent | Jim Abbott | — | Milwaukee Brewers | Free agent signing |
| Jan 27, 1999 | Signed as free agent | Carlos Baerga | — | St. Louis Cardinals | Free agent signing |
| Jan 27, 1999 | Signed as free agent | Mike Magnante | — | Anaheim Angels | Free agent signing |
| Jan 27, 1999 | Signed as free agent | Bob Wells | — | Minnesota Twins | Free agent signing |
| Jan 26, 1999 | Released | Tarrik Brock | Seattle Mariners | — | Release |
| Jan 26, 1999 | Signed as free agent | John Cangelosi | — | Chicago White Sox | Free agent signing |
| Jan 26, 1999 | Released | Alberto Castillo | New York Yankees | — | Release |
| Jan 26, 1999 | Signed as free agent | Jason Grimsley | — | New York Yankees | Free agent signing |
| Jan 26, 1999 | Signed as free agent | Darrin Jackson | — | Chicago White Sox | Free agent signing |
| Jan 26, 1999 | Signed as free agent | Mike Morgan | — | Texas Rangers | Free agent signing |
| Jan 26, 1999 | Signed as free agent | Tim Raines | — | Oakland Athletics | Free agent signing |
| Jan 26, 1999 | Signed as free agent | Dave Stevens | — | Cleveland Indians | Free agent signing |
| Jan 25, 1999 | Signed as free agent | Billy McMillon | — | Philadelphia Phillies | Free agent signing |
| Jan 25, 1999 | Signed as free agent | Chris Michalak | — | Anaheim Angels | Free agent signing |
| Jan 25, 1999 | Signed as free agent | Steve Mintz | — | Anaheim Angels | Free agent signing |
| Jan 25, 1999 | Signed as free agent | Steve Scarsone | — | Kansas City Royals | Free agent signing |
| Jan 25, 1999 | Signed as free agent | Tony Tarasco | — | Kansas City Royals | Free agent signing |
| Jan 22, 1999 | Signed as free agent | Jeff Ball | — | Oakland Athletics | Free agent signing |
| Jan 22, 1999 | Signed as free agent | Chris Haney | — | Los Angeles Dodgers | Free agent signing |
| Jan 22, 1999 | Signed as free agent | Ken Huckaby | — | Arizona Diamondbacks | Free agent signing |
| Jan 21, 1999 | Signed as free agent | Alex Diaz | — | Houston Astros | Free agent signing |
| Jan 21, 1999 | Signed as free agent | Randy Knorr | — | Houston Astros | Free agent signing |
| Jan 21, 1999 | Signed as free agent | Jeff McCurry | — | Houston Astros | Free agent signing |
| Jan 21, 1999 | Signed | Ray Olmedo | — | Cincinnati Reds | Amateur free agent signing |
| Jan 21, 1999 | Signed as free agent | Bob Scanlan | — | Houston Astros | Free agent signing |
| Jan 21, 1999 | Signed as free agent | Brian Williams | — | Houston Astros | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Norm Charlton | — | Tampa Bay Devil Rays | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Steve Cooke | — | Tampa Bay Devil Rays | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Steve Ontiveros | — | Tampa Bay Devil Rays | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Chance Sanford | — | Los Angeles Dodgers | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Everett Stull | — | Atlanta Braves | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Marc Valdes | — | Tampa Bay Devil Rays | Free agent signing |
| Jan 20, 1999 | Signed as free agent | Bobby Witt | — | Tampa Bay Devil Rays | Free agent signing |
| Jan 19, 1999 | Signed as free agent | Willie Greene | — | Toronto Blue Jays | Free agent signing |
| Jan 19, 1999 | Signed as free agent | Vicente Palacios | — | Toronto Blue Jays | Free agent signing |
| Jan 19, 1999 | Signed as free agent | Ryan Thompson | — | Houston Astros | Free agent signing |
| Jan 19, 1999 | Signed as free agent | Allen Watson | — | New York Mets | Free agent signing |
| Jan 18, 1999 | Signed as free agent | Joey Cora | — | Toronto Blue Jays | Free agent signing |
| Jan 18, 1999 | Signed as free agent | Joe Hudson | — | Texas Rangers | Free agent signing |
| Jan 18, 1999 | Signed | Luis Jimenez | — | Oakland Athletics | Amateur free agent signing |
| Jan 18, 1999 | Signed as free agent | Hector Ortiz | — | Los Angeles Dodgers | Free agent signing |
| Jan 18, 1999 | Signed as free agent | Todd Van Poppel | — | Pittsburgh Pirates | Free agent signing |
| Jan 17, 1999 | Signed as free agent | Scott Servais | — | San Francisco Giants | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Robert Ellis | — | Houston Astros | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Gus Gandarillas | — | Pittsburgh Pirates | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Ricardo Jordan | — | Los Angeles Dodgers | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Jalal Leach | — | San Francisco Giants | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Scott Livingstone | — | Los Angeles Dodgers | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Mike Mohler | — | St. Louis Cardinals | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Luis Rivera | — | Anaheim Angels | Free agent signing |
| Jan 15, 1999 | Signed as free agent | Heathcliff Slocumb | — | Baltimore Orioles | Free agent signing |
| Jan 14, 1999 | Signed as free agent | Brent Cookson | — | Los Angeles Dodgers | Free agent signing |
| Jan 14, 1999 | Signed as free agent | Terry Mathews | — | Kansas City Royals | Free agent signing |
| Jan 14, 1999 | Signed as free agent | Allen McDill | — | Kansas City Royals | Free agent signing |
| Jan 14, 1999 | Signed as free agent | Hal Morris | — | Cincinnati Reds | Free agent signing |
| Jan 14, 1999 | Trade | Paul Bako | Detroit Tigers | Houston Astros | Trade |
| Jan 14, 1999 | Trade | Dean Crow | Detroit Tigers | Houston Astros | Trade |
| Jan 14, 1999 | Trade | Mark Persails | Detroit Tigers | Houston Astros | Trade |
| Jan 14, 1999 | Trade | Brian Powell | Detroit Tigers | Houston Astros | Trade |
| Jan 14, 1999 | Trade | Carlos Villalobos | Detroit Tigers | Houston Astros | Trade |
| Jan 14, 1999 | Trade | Brad Ausmus | Houston Astros | Detroit Tigers | Trade |
| Jan 14, 1999 | Trade | C. J. Nitkowski | Houston Astros | Detroit Tigers | Trade |
| Jan 13, 1999 | Signed as free agent | Billy Ashley | — | Tampa Bay Devil Rays | Free agent signing |
| Jan 13, 1999 | Signed as free agent | Darron Cox | — | Montreal Expos | Free agent signing |
| Jan 13, 1999 | Signed as free agent | Marcus Jensen | — | St. Louis Cardinals | Free agent signing |
| Jan 13, 1999 | Signed as free agent | John Marzano | — | Texas Rangers | Free agent signing |
| Jan 13, 1999 | Signed as free agent | Derrick May | — | Montreal Expos | Free agent signing |
| Jan 12, 1999 | Signed as free agent | Darren Bragg | — | St. Louis Cardinals | Free agent signing |
| Jan 12, 1999 | Signed as free agent | Greg Cadaret | — | Los Angeles Dodgers | Free agent signing |
| Jan 12, 1999 | Signed as free agent | Frank Castillo | — | Arizona Diamondbacks | Free agent signing |
| Jan 12, 1999 | Signed as free agent | Matt Luke | — | Anaheim Angels | Free agent signing |
| Jan 12, 1999 | Signed as free agent | Mike Munoz | — | Texas Rangers | Free agent signing |
| Jan 12, 1999 | Signed | Wandy Rodriguez | — | Houston Astros | Amateur free agent signing |
| Jan 12, 1999 | Signed as free agent | Pedro Valdes | — | Boston Red Sox | Free agent signing |
| Jan 12, 1999 | Trade | Joe Sutton | Chicago White Sox | Los Angeles Dodgers | Trade |
| Jan 12, 1999 | Trade | Darren Hall | Los Angeles Dodgers | Chicago White Sox | Trade |
| Jan 11, 1999 | Signed as free agent | Rich Becker | — | Milwaukee Brewers | Free agent signing |
| Jan 11, 1999 | Released | Doug Bochtler | Los Angeles Dodgers | — | Release |
| Jan 11, 1999 | Signed as free agent | Dave Hansen | — | Los Angeles Dodgers | Free agent signing |
| Jan 11, 1999 | Signed as free agent | Brian Johnson | — | Cincinnati Reds | Free agent signing |
| Jan 11, 1999 | Signed as free agent | Doug Jones | — | Oakland Athletics | Free agent signing |
| Jan 11, 1999 | Signed as free agent | Tim Laker | — | Los Angeles Dodgers | Free agent signing |
| Jan 11, 1999 | Signed as free agent | Bry Nelson | — | Chicago Cubs | Free agent signing |
| Jan 11, 1999 | Signed as free agent | Pat Rapp | — | Boston Red Sox | Free agent signing |
| Jan 11, 1999 | Signed | Francisco Rosario | — | Toronto Blue Jays | Amateur free agent signing |
| Jan 10, 1999 | Trade | Rich Pratt | Chicago White Sox | New York Yankees | Trade |
| Jan 8, 1999 | Signed as free agent | Mike Oquist | — | Oakland Athletics | Free agent signing |
| Jan 8, 1999 | Signed as free agent | Bill Swift | — | Seattle Mariners | Free agent signing |
| Jan 7, 1999 | Signed as free agent | Tony Fossas | — | Texas Rangers | Free agent signing |
| Jan 7, 1999 | Released | Agustin Montero | Oakland Athletics | — | Release |
| Jan 7, 1999 | Signed as free agent | Marc Newfield | — | Oakland Athletics | Free agent signing |
| Jan 6, 1999 | Signed as free agent | Jamie Arnold | — | Los Angeles Dodgers | Free agent signing |
| Jan 6, 1999 | Signed as free agent | Wayne Kirby | — | Toronto Blue Jays | Free agent signing |
| Jan 6, 1999 | Signed as free agent | Jason Simontacchi | — | Pittsburgh Pirates | Free agent signing |
| Jan 6, 1999 | Trade | Pablo Minaya | Florida Marlins | Cincinnati Reds | Trade |
| Jan 6, 1999 | Trade | Pat Watkins | Cincinnati Reds | Florida Marlins | Trade |
| Jan 5, 1999 | Signed as free agent | Rheal Cormier | — | Boston Red Sox | Free agent signing |
| Jan 5, 1999 | Signed as free agent | Kip Gross | — | Boston Red Sox | Free agent signing |
| Jan 5, 1999 | Signed as free agent | Jeff Manto | — | Cleveland Indians | Free agent signing |
| Jan 5, 1999 | Signed as free agent | Dave Telgheder | — | Cleveland Indians | Free agent signing |
| Jan 5, 1999 | Signed as free agent | Chris Turner | — | Cleveland Indians | Free agent signing |
| Jan 4, 1999 | Signed as free agent | Paul Abbott | — | Seattle Mariners | Free agent signing |
| Jan 4, 1999 | Signed as free agent | Jim Brower | — | Cleveland Indians | Free agent signing |
| Jan 4, 1999 | Signed | Chin-Feng Chen | — | Los Angeles Dodgers | Amateur free agent signing |
| Jan 4, 1999 | Signed as free agent | Osvaldo Fernandez | — | San Francisco Giants | Free agent signing |
| Jan 4, 1999 | Signed as free agent | Kevin Jarvis | — | Oakland Athletics | Free agent signing |
| Jan 4, 1999 | Signed as free agent | Terry Steinbach | — | Minnesota Twins | Free agent signing |
| Jan 4, 1999 | Signed as free agent | Derrick White | — | Chicago Cubs | Free agent signing |
| Jan 3, 1999 | Signed as free agent | P. J. Forbes | — | Texas Rangers | Free agent signing |
| Jan 3, 1999 | Signed as free agent | Brady Raggio | — | Texas Rangers | Free agent signing |
| Jan 2, 1999 | Signed as free agent | Jose Herrera | — | Baltimore Orioles | Free agent signing |
| Jan 1, 1999 | Signed as free agent | Matt Herges | — | Los Angeles Dodgers | Free agent signing |
Every row is mapped onto the same trade / signing / release vocabulary the modern feed uses, with the era’s own type description kept on each row. Club names are the names of the day (the Boston Braves years, the Brooklyn Dodgers years), and each links to the franchise it is today. Some dates are only partially known or flagged approximate by the source; they are shown exactly as published, never completed to a fake precise day.