| 2003-03-31 | @ SDN | 1 | W 5-2 | 1-0 | 2 | 61,707 | Kirk Rueter | Brian Lawrence | Felix Rodriguez | Clay Condrey | Tim Worrell | 5 | 2 | 3 |
| 2003-04-01 | @ SDN | 2 | W 8-1 | 2-0 | 1 | 50,605 | Jason Schmidt | Adam Eaton | Jason Schmidt | Adam Eaton | | 13 | 3 | 10 |
| 2003-04-02 | @ SDN | 3 | W 5-3 | 3-0 | 1 | 15,899 | Damian Moss | Oliver Perez | Damian Moss | Oliver Perez | Tim Worrell | 18 | 6 | 12 |
| 2003-04-04 | @ MIL | 4 | W 7-5 | 4-0 | 1 | 42,570 | Ryan Jensen | Todd Ritchie | Jim Brower | Luis Vizcaino | Tim Worrell | 25 | 11 | 14 |
| 2003-04-05 | @ MIL | 5 | W 6-5 | 5-0 | 1 | 16,255 | Kurt Ainsworth | Ben Sheets | Kurt Ainsworth | Ben Sheets | Scott Eyre | 31 | 16 | 15 |
| 2003-04-06 | @ MIL | 6 | W 5-0 | 6-0 | 1 | 16,101 | Kirk Rueter | Wayne Franklin | Kirk Rueter | Wayne Franklin | Jim Brower | 36 | 16 | 20 |
| 2003-04-07 | vs SDN | 7 | W 7-4 | 7-0 | 1 | 41,915 | Jason Schmidt | Oliver Perez | Tim Worrell | Mike Bynum | | 43 | 20 | 23 |
| 2003-04-08 | vs SDN | 8 | L 4-9 | 7-1 | 1 | 36,388 | Damian Moss | Jake Peavy | Jake Peavy | Scott Eyre | | 47 | 29 | 18 |
| 2003-04-09 | vs SDN | 9 | W 15-11 | 8-1 | 1 | 35,187 | Ryan Jensen | Dennis Tankersley | Joe Nathan | Dennis Tankersley | | 62 | 40 | 22 |
| 2003-04-10 | vs LAN | 10 | W 2-1 | 9-1 | 1 | 38,294 | Kurt Ainsworth | Hideo Nomo | Kurt Ainsworth | Hideo Nomo | Tim Worrell | 64 | 41 | 23 |
| 2003-04-11 | vs LAN | 11 | W 3-2 | 10-1 | 1 | 42,022 | Kirk Rueter | Odalis Perez | Kirk Rueter | Odalis Perez | Tim Worrell | 67 | 43 | 24 |
| 2003-04-13 | vs LAN | 12 | W 5-4 | 11-1 | 1 | 41,672 | Jason Schmidt | Kevin Brown | Jim Brower | Andy Ashby | | 72 | 47 | 25 |
| 2003-04-14 | vs HOU | 13 | W 4-2 | 12-1 | 1 | 35,919 | Damian Moss | Wade Miller | Damian Moss | Wade Miller | Tim Worrell | 76 | 49 | 27 |
| 2003-04-15 | vs HOU | 14 | W 8-4 | 13-1 | 1 | 36,629 | Kurt Ainsworth | Jeriome Robertson | Kurt Ainsworth | Jeriome Robertson | Felix Rodriguez | 84 | 53 | 31 |
| 2003-04-16 | vs HOU | 15 | L 5-8 | 13-2 | 1 | 37,679 | Kirk Rueter | Brian Moehler | Brad Lidge | Jim Brower | Billy Wagner | 89 | 61 | 28 |
| 2003-04-18 | @ LAN | 16 | W 5-1 | 14-2 | 1 | 54,799 | Jason Schmidt | Kevin Brown | Jason Schmidt | Kevin Brown | | 94 | 62 | 32 |
| 2003-04-19 | @ LAN | 17 | W 9-3 | 15-2 | 1 | 50,918 | Damian Moss | Andy Ashby | Damian Moss | Andy Ashby | | 103 | 65 | 38 |
| 2003-04-20 | @ LAN | 18 | L 4-16 | 15-3 | 1 | 39,123 | Kurt Ainsworth | Hideo Nomo | Hideo Nomo | Kurt Ainsworth | | 107 | 81 | 26 |
| 2003-04-22 | @ PIT | 19 | L 2-5 | 15-4 | 1 | 10,650 | Jesse Foppert | Jeff Suppan | Jeff Suppan | Jesse Foppert | | 109 | 86 | 23 |
| 2003-04-23 | @ PIT | 20 | W 4-3 | 16-4 | 1 | 13,009 | Kirk Rueter | Jeff D'Amico | Jim Brower | Julian Tavarez | | 113 | 89 | 24 |
| 2003-04-24 | @ PIT | 21 | W 3-1 | 17-4 | 1 | 15,967 | Damian Moss | Kris Benson | Damian Moss | Kris Benson | Tim Worrell | 116 | 90 | 26 |
| 2003-04-25 | @ PHI | 22 | W 7-4 | 18-4 | 1 | 20,650 | Kurt Ainsworth | Vicente Padilla | Joe Nathan | Vicente Padilla | | 123 | 94 | 29 |
| 2003-04-26 | @ PHI | 23 | L 2-10 | 18-5 | 1 | 19,464 | Jerome Williams | Brandon Duckworth | Brandon Duckworth | Jerome Williams | Carlos Silva | 125 | 104 | 21 |
| 2003-04-27 | @ PHI | 24 | L 0-1 | 18-6 | 1 | 40,016 | Jesse Foppert | Kevin Millwood | Kevin Millwood | Jesse Foppert | | 125 | 105 | 20 |
| 2003-04-29 | vs CHN | 25 | L 2-4 | 18-7 | 1 | 39,839 | Kirk Rueter | Kerry Wood | Kerry Wood | Kirk Rueter | Joe Borowski | 127 | 109 | 18 |
| 2003-04-30 | vs CHN | 26 | W 5-0 | 19-7 | 1 | 40,124 | Jason Schmidt | Matt Clement | Jason Schmidt | Matt Clement | | 132 | 109 | 23 |
| 2003-05-01 | vs CHN | 27 | L 1-5 | 19-8 | 1 | 41,524 | Damian Moss | Mark Prior | Juan Cruz | Tim Worrell | | 133 | 114 | 19 |
| 2003-05-02 | vs CIN | 28 | L 1-5 | 19-9 | 1 | 35,486 | Kurt Ainsworth | Danny Graves | Danny Graves | Kurt Ainsworth | | 134 | 119 | 15 |
| 2003-05-03 | vs CIN | 29 | W 9-6 | 20-9 | 1 | 40,077 | Jesse Foppert | Paul Wilson | Jesse Foppert | Paul Wilson | Tim Worrell | 143 | 125 | 18 |
| 2003-05-04 | vs CIN | 30 | W 6-1 | 21-9 | 1 | 41,163 | Kirk Rueter | Ryan Dempster | Kirk Rueter | Ryan Dempster | | 149 | 126 | 23 |
| 2003-05-06 | @ FLO | 31 | W 4-2 | 22-9 | 1 | 11,701 | Jason Schmidt | Carl Pavano | Joe Nathan | Armando Almanza | Tim Worrell | 153 | 128 | 25 |
| 2003-05-07 | @ FLO | 32 | W 3-2 | 23-9 | 1 | 11,464 | Damian Moss | Josh Beckett | Damian Moss | Josh Beckett | Tim Worrell | 156 | 130 | 26 |
| 2003-05-08 | @ FLO | 33 | W 3-2 | 24-9 | 1 | 13,812 | Kurt Ainsworth | Brad Penny | Joe Nathan | Braden Looper | Tim Worrell | 159 | 132 | 27 |
| 2003-05-09 | @ ATL | 34 | W 9-2 | 25-9 | 1 | 32,040 | Jesse Foppert | Greg Maddux | Jesse Foppert | Greg Maddux | Jim Brower | 168 | 134 | 34 |
| 2003-05-10 | @ ATL | 35 | L 3-6 | 25-10 | 1 | 39,357 | Kirk Rueter | Horacio Ramirez | Kevin Gryboski | Joe Nathan | | 171 | 140 | 31 |
| 2003-05-11 | @ ATL | 36 | L 3-7 | 25-11 | 1 | 28,329 | Jason Schmidt | Mike Hampton | Mike Hampton | Jason Schmidt | | 174 | 147 | 27 |
| 2003-05-12 | vs MON | 37 | L 3-4 | 25-12 | 1 | 33,071 | Damian Moss | Zach Day | Zach Day | Damian Moss | Rocky Biddle | 177 | 151 | 26 |
| 2003-05-13 | vs MON | 38 | L 4-6 | 25-13 | 1 | 32,991 | Kurt Ainsworth | Tomo Ohka | Dan Smith | Kurt Ainsworth | Rocky Biddle | 181 | 157 | 24 |
| 2003-05-14 | vs MON | 39 | L 3-6 | 25-14 | 1 | 38,963 | Jesse Foppert | Claudio Vargas | Claudio Vargas | Jesse Foppert | | 184 | 163 | 21 |
| 2003-05-15 | vs NYN | 40 | W 11-3 | 26-14 | 1 | 36,542 | Kirk Rueter | Al Leiter | Kirk Rueter | Al Leiter | | 195 | 166 | 29 |
| 2003-05-16 | vs NYN | 41 | W 7-5 | 27-14 | 1 | 39,160 | Jason Schmidt | Pedro Astacio | Joe Nathan | David Weathers | Tim Worrell | 202 | 171 | 31 |
| 2003-05-17 | vs NYN | 42 | L 1-5 | 27-15 | 1 | 42,259 | Damian Moss | Steve Trachsel | Steve Trachsel | Damian Moss | | 203 | 176 | 27 |
| 2003-05-18 | vs NYN | 43 | L 1-5 | 27-16 | 1 | 42,590 | Kurt Ainsworth | Tom Glavine | Tom Glavine | Kurt Ainsworth | | 204 | 181 | 23 |
| 2003-05-19 | @ ARI | 44 | L 3-4 | 27-17 | 1 | 32,037 | Jesse Foppert | Curt Schilling | Matt Mantei | Tim Worrell | | 207 | 185 | 22 |
| 2003-05-20 | @ ARI | 45 | W 6-5 | 28-17 | 1 | 37,575 | Kirk Rueter | Elmer Dessens | Kirk Rueter | Elmer Dessens | Tim Worrell | 213 | 190 | 23 |
| 2003-05-21 | @ ARI | 46 | W 6-0 | 29-17 | 1 | 35,886 | Jason Schmidt | Miguel Batista | Jason Schmidt | Miguel Batista | | 219 | 190 | 29 |
| 2003-05-23 | @ COL | 47 | L 7-10 | 29-18 | 1 | 30,043 | Damian Moss | Shawn Chacon | Shawn Chacon | Damian Moss | | 226 | 200 | 26 |
| 2003-05-24 | @ COL | 48 | W 5-1 | 30-18 | 1 | 31,475 | Kurt Ainsworth | Scott Elarton | Kurt Ainsworth | Scott Elarton | | 231 | 201 | 30 |
| 2003-05-25 | @ COL | 49 | L 1-5 | 30-19 | 1 | 33,723 | Jesse Foppert | Darren Oliver | Darren Oliver | Jesse Foppert | | 232 | 206 | 26 |
| 2003-05-26 | @ COL | 50 | L 7-12 | 30-20 | 2 | 28,340 | Kirk Rueter | Jason Jennings | Brian Fuentes | Joe Nathan | | 239 | 218 | 21 |
| 2003-05-27 | vs ARI | 51 | W 4-3 | 31-20 | 1 | 36,693 | Jason Schmidt | Byung-Hyun Kim | Felix Rodriguez | Matt Mantei | | 243 | 221 | 22 |
| 2003-05-28 | vs ARI | 52 | W 10-2 | 32-20 | 1 | 37,447 | Damian Moss | John Patterson | Damian Moss | John Patterson | | 253 | 223 | 30 |
| 2003-05-30 | vs COL | 53 | W 6-2 | 33-20 | 1 | 38,439 | Kurt Ainsworth | Darren Oliver | Kurt Ainsworth | Darren Oliver | | 259 | 225 | 34 |
| 2003-05-31 | vs COL | 54 | W 2-1 | 34-20 | 1 | 40,256 | Jesse Foppert | Jason Jennings | Jesse Foppert | Jason Jennings | Tim Worrell | 261 | 226 | 35 |
| 2003-06-01 | vs COL | 55 | W 4-0 | 35-20 | 1 | 41,404 | Kirk Rueter | Aaron Cook | Kirk Rueter | Aaron Cook | | 265 | 226 | 39 |
| 2003-06-02 | vs COL | 56 | L 1-4 | 35-21 | 1 | 34,231 | Jason Schmidt | Shawn Chacon | Shawn Chacon | Jason Schmidt | Jose Jimenez | 266 | 230 | 36 |
| 2003-06-03 | vs MIN | 57 | L 4-6 | 35-22 | 1 | 34,713 | Damian Moss | Joe Mays | Joe Mays | Damian Moss | Eddie Guardado | 270 | 236 | 34 |
| 2003-06-04 | vs MIN | 58 | W 4-3 | 36-22 | 1 | 35,319 | Jerome Williams | Brad Radke | Tim Worrell | Juan Rincon | | 274 | 239 | 35 |
| 2003-06-05 | vs MIN | 59 | L 2-5 | 36-23 | 1 | 35,783 | Jesse Foppert | Kyle Lohse | Kyle Lohse | Jesse Foppert | Eddie Guardado | 276 | 244 | 32 |
| 2003-06-06 | vs DET | 60 | W 5-3 | 37-23 | 1 | 41,554 | Kirk Rueter | Jeremy Bonderman | Kirk Rueter | Jeremy Bonderman | Tim Worrell | 281 | 247 | 34 |
| 2003-06-07 | vs DET | 61 | W 7-5 | 38-23 | 1 | 40,060 | Jason Schmidt | Mike Maroth | Jason Schmidt | Mike Maroth | | 288 | 252 | 36 |
| 2003-06-08 | vs DET | 62 | W 7-6 | 39-23 | 1 | 41,177 | Damian Moss | Nate Cornejo | Joe Nathan | Franklyn German | Tim Worrell | 295 | 258 | 37 |
| 2003-06-10 | @ CHA | 63 | L 3-5 | 39-24 | 1 | 23,837 | Jerome Williams | Jon Garland | Jon Garland | Joe Nathan | | 298 | 263 | 35 |
| 2003-06-11 | @ CHA | 64 | W 11-4 | 40-24 | 1 | 19,114 | Jesse Foppert | Mark Buehrle | Jesse Foppert | Mark Buehrle | | 309 | 267 | 42 |
| 2003-06-12 | @ CHA | 65 | W 8-4 | 41-24 | 1 | 22,827 | Kirk Rueter | Bartolo Colon | Joe Nathan | Bartolo Colon | | 317 | 271 | 46 |
| 2003-06-13 | @ KCA | 66 | L 1-6 | 41-25 | 1 | 31,426 | Jason Schmidt | Chris George | Chris George | Jason Schmidt | | 318 | 277 | 41 |
| 2003-06-14 | @ KCA | 67 | W 7-4 | 42-25 | 1 | 38,261 | Damian Moss | D.J. Carrasco | Damian Moss | Les Walrond | | 325 | 281 | 44 |
| 2003-06-15 | @ KCA | 68 | L 4-5 | 42-26 | 1 | 29,631 | Jerome Williams | Jose Lima | Mike MacDougal | Tim Worrell | | 329 | 286 | 43 |
| 2003-06-17 | @ LAN | 69 | L 1-4 | 42-27 | 1 | 48,077 | Jesse Foppert | Kevin Brown | Kevin Brown | Jesse Foppert | Eric Gagne | 330 | 290 | 40 |
| 2003-06-18 | @ LAN | 70 | L 2-8 | 42-28 | 2 | 50,247 | Kirk Rueter | Kazuhisa Ishii | Kazuhisa Ishii | Kirk Rueter | | 332 | 298 | 34 |
| 2003-06-19 | @ LAN | 71 | W 2-0 | 43-28 | 1 | 51,047 | Jason Schmidt | Odalis Perez | Jason Schmidt | Odalis Perez | | 334 | 298 | 36 |
| 2003-06-20 | @ OAK | 72 | L 3-5 | 43-29 | 2 | 47,074 | Damian Moss | Aaron Harang | Aaron Harang | Damian Moss | Keith Foulke | 337 | 303 | 34 |
| 2003-06-21 | @ OAK | 73 | W 6-4 | 44-29 | 2 | 52,888 | Jerome Williams | Tim Hudson | Jerome Williams | Tim Hudson | Tim Worrell | 343 | 307 | 36 |
| 2003-06-22 | @ OAK | 74 | L 5-6 | 44-30 | 2 | 55,413 | Jesse Foppert | Ted Lilly | Ted Lilly | Chad Zerbe | Keith Foulke | 348 | 313 | 35 |
| 2003-06-23 | vs LAN | 75 | W 3-2 | 45-30 | 1 | 42,474 | Kirk Rueter | Kazuhisa Ishii | Felix Rodriguez | Eric Gagne | | 351 | 315 | 36 |
| 2003-06-24 | vs LAN | 76 | W 2-1 | 46-30 | 1 | 42,648 | Jason Schmidt | Odalis Perez | Jason Schmidt | Odalis Perez | | 353 | 316 | 37 |
| 2003-06-25 | vs LAN | 77 | L 0-6 | 46-31 | 1 | 42,632 | Damian Moss | Hideo Nomo | Hideo Nomo | Damian Moss | | 353 | 322 | 31 |
| 2003-06-27 | vs OAK | 78 | W 6-0 | 47-31 | 1 | 42,604 | Jerome Williams | Ted Lilly | Jerome Williams | Ted Lilly | | 359 | 322 | 37 |
| 2003-06-28 | vs OAK | 79 | W 8-7 | 48-31 | 1 | 42,519 | Kirk Rueter | Barry Zito | Felix Rodriguez | Keith Foulke | | 367 | 329 | 38 |
| 2003-06-29 | vs OAK | 80 | L 2-5 | 48-32 | 1 | 42,508 | Jesse Foppert | Mark Mulder | Mark Mulder | Jesse Foppert | Keith Foulke | 369 | 334 | 35 |
| 2003-06-30 | @ SLN | 81 | W 5-1 | 49-32 | 1 | 33,873 | Jason Schmidt | Dan Haren | Jason Schmidt | Dan Haren | | 374 | 335 | 39 |
| 2003-07-01 | @ SLN | 82 | W 5-1 | 50-32 | 1 | 39,894 | Jim Brower | Woody Williams | Jim Brower | Woody Williams | | 379 | 336 | 43 |
| 2003-07-02 | @ SLN | 83 | W 4-1 | 51-32 | 1 | 33,835 | Jerome Williams | Garrett Stephenson | Jerome Williams | Garrett Stephenson | Tim Worrell | 383 | 337 | 46 |
| 2003-07-03 | @ SLN | 84 | L 5-9 | 51-33 | 1 | 38,129 | Kirk Rueter | Jason Simontacchi | Jason Simontacchi | Kirk Rueter | | 388 | 346 | 42 |
| 2003-07-04 | @ SDN | 85 | W 8-6 | 52-33 | 1 | 42,379 | Jesse Foppert | Jake Peavy | Jesse Foppert | Jake Peavy | Tim Worrell | 396 | 352 | 44 |
| 2003-07-05 | @ SDN | 86 | L 2-5 | 52-34 | 1 | 56,474 | Jason Schmidt | Kevin Jarvis | Kevin Jarvis | Jason Schmidt | Rod Beck | 398 | 357 | 41 |
| 2003-07-06 | @ SDN | 87 | W 3-2 | 53-34 | 1 | 24,365 | Damian Moss | Brian Lawrence | Felix Rodriguez | Luther Hackman | Tim Worrell | 401 | 359 | 42 |
| 2003-07-07 | vs SLN | 88 | W 5-1 | 54-34 | 1 | 42,674 | Jerome Williams | Garrett Stephenson | Jerome Williams | Garrett Stephenson | | 406 | 360 | 46 |
| 2003-07-08 | vs SLN | 89 | W 8-3 | 55-34 | 1 | 42,672 | Kirk Rueter | Dan Haren | Jim Brower | Dan Haren | | 414 | 363 | 51 |
| 2003-07-09 | @ COL | 90 | L 7-11 | 55-35 | 1 | 31,139 | Jesse Foppert | Aaron Cook | Aaron Cook | Jesse Foppert | | 421 | 374 | 47 |
| 2003-07-10 | @ COL | 91 | L 3-11 | 55-36 | 1 | 30,954 | Brian Powell | Darren Oliver | Darren Oliver | Brian Powell | | 424 | 385 | 39 |
| 2003-07-11 | @ ARI | 92 | W 10-7 | 56-36 | 1 | 44,105 | Jason Schmidt | Miguel Batista | Jason Schmidt | Miguel Batista | Felix Rodriguez | 434 | 392 | 42 |
| 2003-07-12 | @ ARI | 93 | W 8-1 | 57-36 | 1 | 45,653 | Jerome Williams | Curt Schilling | Jerome Williams | Curt Schilling | | 442 | 393 | 49 |
| 2003-07-13 | @ ARI | 94 | L 4-7 | 57-37 | 1 | 44,719 | Jim Brower | Brandon Webb | Brandon Webb | Jim Brower | Matt Mantei | 446 | 400 | 46 |
| 2003-07-17 | vs COL | 95 | W 8-4 | 58-37 | 1 | 41,052 | Damian Moss | Jason Jennings | Damian Moss | Jason Jennings | | 454 | 404 | 50 |
| 2003-07-18 | vs COL | 96 | W 7-0 | 59-37 | 1 | 41,690 | Jim Brower | Darren Oliver | Jim Brower | Darren Oliver | | 461 | 404 | 57 |
| 2003-07-19 | vs COL | 97 | W 5-3 | 60-37 | 1 | 42,607 | Jason Schmidt | Shawn Chacon | Jason Schmidt | Shawn Chacon | Tim Worrell | 466 | 407 | 59 |
| 2003-07-20 | vs COL | 98 | W 8-4 | 61-37 | 1 | 42,620 | Jesse Foppert | Denny Neagle | Jesse Foppert | Denny Neagle | | 474 | 411 | 63 |
| 2003-07-21 | vs ARI | 99 | W 5-4 | 62-37 | 1 | 41,421 | Jerome Williams | Elmer Dessens | Chad Zerbe | Elmer Dessens | Tim Worrell | 479 | 415 | 64 |
| 2003-07-22 | vs ARI | 100 | W 3-1 | 63-37 | 1 | 41,340 | Damian Moss | Curt Schilling | Damian Moss | Curt Schilling | Tim Worrell | 482 | 416 | 66 |
| 2003-07-23 | vs ARI | 101 | W 7-1 | 64-37 | 1 | 41,512 | Jim Brower | Miguel Batista | Jim Brower | Miguel Batista | | 489 | 417 | 72 |
| 2003-07-24 | vs ARI | 102 | W 3-2 | 65-37 | 1 | 42,666 | Chad Zerbe | Brandon Webb | Tim Worrell | Mike Myers | | 492 | 419 | 73 |
| 2003-07-25 | vs SDN | 103 | W 5-2 | 66-37 | 1 | 41,552 | Kirk Rueter | Adam Eaton | Felix Rodriguez | Jay Witasick | | 497 | 421 | 76 |
| 2003-07-26 | vs SDN | 104 | L 1-2 | 66-38 | 1 | 42,521 | Jerome Williams | Kevin Jarvis | Kevin Jarvis | Jerome Williams | Rod Beck | 498 | 423 | 75 |
| 2003-07-27 | vs SDN | 105 | W 6-2 | 67-38 | 1 | 42,530 | Jesse Foppert | Jake Peavy | Jesse Foppert | Jake Peavy | | 504 | 425 | 79 |
| 2003-07-29 | @ CHN | 106 | L 0-3 | 67-39 | 1 | 40,221 | Damian Moss | Matt Clement | Matt Clement | Damian Moss | | 504 | 428 | 76 |
| 2003-07-30 | @ CHN | 107 | W 6-3 | 68-39 | 1 | 39,973 | Jason Schmidt | Kerry Wood | Jason Schmidt | Kerry Wood | | 510 | 431 | 79 |
| 2003-07-31 | @ CHN | 108 | L 4-9 | 68-40 | 1 | 39,422 | Jim Brower | Carlos Zambrano | Carlos Zambrano | Jim Brower | | 514 | 440 | 74 |
| 2003-08-01 | @ CIN | 109 | L 3-5 | 68-41 | 1 | 39,291 | Jerome Williams | Paul Wilson | Chris Reitsma | Felix Rodriguez | | 517 | 445 | 72 |
| 2003-08-02 | @ CIN | 110 | L 4-5 | 68-42 | 1 | 36,682 | Jesse Foppert | Josh Hall | Ryan Wagner | Felix Rodriguez | Felix Heredia | 521 | 450 | 71 |
| 2003-08-03 | @ CIN | 111 | W 7-3 | 69-42 | 1 | 35,840 | Dustin Hermanson | Jimmy Haynes | Dustin Hermanson | Jimmy Haynes | | 528 | 453 | 75 |
| 2003-08-05 | vs PIT | 112 | W 3-0 | 70-42 | 1 | 41,501 | Jason Schmidt | Kip Wells | Jason Schmidt | Kip Wells | Tim Worrell | 531 | 453 | 78 |
| 2003-08-06 | vs PIT | 113 | L 0-2 | 70-43 | 1 | 41,662 | Sidney Ponson | Josh Fogg | Julian Tavarez | Sidney Ponson | | 531 | 455 | 76 |
| 2003-08-07 | vs PIT | 114 | W 7-5 | 71-43 | 1 | 42,334 | Jerome Williams | Ryan Vogelsong | Scott Eyre | Brian Boehringer | Tim Worrell | 538 | 460 | 78 |
| 2003-08-08 | vs PHI | 115 | W 9-1 | 72-43 | 1 | 42,595 | Jesse Foppert | Randy Wolf | Jesse Foppert | Randy Wolf | | 547 | 461 | 86 |
| 2003-08-09 | vs PHI | 116 | L 6-8 | 72-44 | 1 | 42,572 | Dustin Hermanson | Vicente Padilla | Turk Wendell | Jim Brower | | 553 | 469 | 84 |
| 2003-08-10 | vs PHI | 117 | W 5-2 | 73-44 | 1 | 42,520 | Kevin Correia | Brett Myers | Kevin Correia | Brett Myers | | 558 | 471 | 87 |
| 2003-08-12 | @ NYN | 118 | L 4-5 | 73-45 | 1 | 37,461 | Sidney Ponson | Aaron Heilman | Aaron Heilman | Sidney Ponson | David Weathers | 562 | 476 | 86 |
| 2003-08-13 | @ NYN | 119 | L 2-9 | 73-46 | 1 | 31,759 | Jerome Williams | Steve Trachsel | Steve Trachsel | Jerome Williams | | 564 | 485 | 79 |
| 2003-08-15 | @ MON | 120 | L 1-4 | 73-47 | 1 | 10,551 | Jesse Foppert | Livan Hernandez | Livan Hernandez | Jesse Foppert | | 565 | 489 | 76 |
| 2003-08-16 | @ MON | 121 | L 1-4 | 73-48 | 1 | 16,446 | Jason Schmidt | Zach Day | Zach Day | Jason Schmidt | Rocky Biddle | 566 | 493 | 73 |
| 2003-08-17 | @ MON | 122 | L 2-4 | 73-49 | 1 | 17,665 | Sidney Ponson | Tomo Ohka | Rocky Biddle | Sidney Ponson | | 568 | 497 | 71 |
| 2003-08-18 | @ MON | 123 | L 0-4 | 73-50 | 1 | 9,224 | Dustin Hermanson | Javier Vazquez | Javier Vazquez | Dustin Hermanson | | 568 | 501 | 67 |
| 2003-08-19 | vs ATL | 124 | W 5-4 | 74-50 | 1 | 42,307 | Jerome Williams | Russ Ortiz | Tim Worrell | Ray King | | 573 | 505 | 68 |
| 2003-08-20 | vs ATL | 125 | W 2-1 | 75-50 | 1 | 41,974 | Jesse Foppert | Shane Reynolds | Joe Nathan | Kevin Gryboski | | 575 | 506 | 69 |
| 2003-08-21 | vs ATL | 126 | W 4-3 | 76-50 | 1 | 41,745 | Jason Schmidt | Horacio Ramirez | Felix Rodriguez | Trey Hodges | | 579 | 509 | 70 |
| 2003-08-22 | vs FLO | 127 | W 6-4 | 77-50 | 1 | 42,244 | Sidney Ponson | Dontrelle Willis | Sidney Ponson | Dontrelle Willis | Tim Worrell | 585 | 513 | 72 |
| 2003-08-23 | vs FLO | 128 | W 3-2 | 78-50 | 1 | 42,189 | Dustin Hermanson | Josh Beckett | Jim Brower | Josh Beckett | Tim Worrell | 588 | 515 | 73 |
| 2003-08-24 | vs FLO | 129 | L 4-7 | 78-51 | 1 | 41,886 | Kirk Rueter | Carl Pavano | Carl Pavano | Kirk Rueter | | 592 | 522 | 70 |
| 2003-08-26 | @ COL | 130 | W 3-1 | 79-51 | 1 | 24,100 | Jason Schmidt | Darren Oliver | Jason Schmidt | Darren Oliver | Tim Worrell | 595 | 523 | 72 |
| 2003-08-27 | @ COL | 131 | W 6-4 | 80-51 | 1 | 24,972 | Sidney Ponson | Jose Jimenez | Sidney Ponson | Jose Jimenez | Tim Worrell | 601 | 527 | 74 |
| 2003-08-28 | @ COL | 132 | L 1-6 | 80-52 | 1 | 23,645 | Kevin Correia | Jason Jennings | Jason Jennings | Kevin Correia | | 602 | 533 | 69 |
| 2003-08-29 | @ ARI | 133 | L 4-5 | 80-53 | 1 | 39,087 | Kirk Rueter | Miguel Batista | Miguel Batista | Kirk Rueter | Matt Mantei | 606 | 538 | 68 |
| 2003-08-30 | @ ARI | 134 | W 2-1 | 81-53 | 1 | 39,383 | Jerome Williams | Randy Johnson | Jerome Williams | Randy Johnson | Tim Worrell | 608 | 539 | 69 |
| 2003-08-31 | @ ARI | 135 | W 3-1 | 82-53 | 1 | 37,836 | Jason Schmidt | Brandon Webb | Jason Schmidt | Brandon Webb | Tim Worrell | 611 | 540 | 71 |
| 2003-09-01 | @ ARI | 136 | W 2-0 | 83-53 | 1 | 33,416 | Sidney Ponson | Curt Schilling | Sidney Ponson | Oscar Villarreal | Tim Worrell | 613 | 540 | 73 |
| 2003-09-02 | vs COL | 137 | W 2-1 | 84-53 | 1 | 39,419 | Kevin Correia | Jose Jimenez | Matt Herges | Adam Bernero | Tim Worrell | 615 | 541 | 74 |
| 2003-09-03 | vs COL | 138 | W 7-6 | 85-53 | 1 | 38,490 | Kirk Rueter | Jason Jennings | Joe Nathan | Brian Fuentes | | 622 | 547 | 75 |
| 2003-09-05 | vs ARI | 139 | L 1-8 | 85-54 | 1 | 41,727 | Jerome Williams | Brandon Webb | Brandon Webb | Jerome Williams | | 623 | 555 | 68 |
| 2003-09-06 | vs ARI | 140 | W 5-4 | 86-54 | 1 | 42,312 | Jason Schmidt | Curt Schilling | Scott Eyre | Matt Mantei | | 628 | 559 | 69 |
| 2003-09-07 | vs ARI | 141 | L 6-9 | 86-55 | 1 | 41,522 | Sidney Ponson | Elmer Dessens | Edgar Gonzalez | Joe Nathan | John Patterson | 634 | 568 | 66 |
| 2003-09-09 | @ SDN | 142 | W 8-3 | 87-55 | 1 | 18,952 | Kevin Correia | Ben Howard | Kevin Correia | Ben Howard | | 642 | 571 | 71 |
| 2003-09-10 | @ SDN | 143 | W 7-1 | 88-55 | 1 | 18,848 | Kirk Rueter | Brian Lawrence | Kirk Rueter | Brian Lawrence | | 649 | 572 | 77 |
| 2003-09-11 | @ SDN | 144 | L 4-5 | 88-56 | 1 | 24,365 | Jerome Williams | Adam Eaton | Mike Matthews | Tim Worrell | | 653 | 577 | 76 |
| 2003-09-12 | vs MIL | 145 | W 8-2 | 89-56 | 1 | 41,015 | Jason Schmidt | Matt Kinney | Jason Schmidt | Matt Kinney | | 661 | 579 | 82 |
| 2003-09-13 | vs MIL | 146 | L 4-5 | 89-57 | 1 | 41,403 | Sidney Ponson | Doug Davis | Doug Davis | Sidney Ponson | Danny Kolb | 665 | 584 | 81 |
| 2003-09-14 | vs MIL | 147 | W 5-4 | 90-57 | 1 | 40,736 | Kevin Correia | Wayne Franklin | Felix Rodriguez | Leo Estrella | | 670 | 588 | 82 |
| 2003-09-15 | vs SDN | 148 | W 8-7 | 91-57 | 1 | 36,542 | Kirk Rueter | Brian Lawrence | Joe Nathan | Jay Witasick | Tim Worrell | 678 | 595 | 83 |
| 2003-09-16 | vs SDN | 149 | W 4-2 | 92-57 | 1 | 37,059 | Jerome Williams | Adam Eaton | Jerome Williams | Adam Eaton | Tim Worrell | 682 | 597 | 85 |
| 2003-09-17 | vs SDN | 150 | W 8-3 | 93-57 | 1 | 40,014 | Jason Schmidt | Mike Bynum | Jason Schmidt | Mike Bynum | | 690 | 600 | 90 |
| 2003-09-18 | vs SDN | 151 | L 3-7 | 93-58 | 1 | 41,163 | Sidney Ponson | Jake Peavy | Jake Peavy | Sidney Ponson | | 693 | 607 | 86 |
| 2003-09-19 | @ LAN | 152 | W 6-4 | 94-58 | 1 | 51,612 | Dustin Hermanson | Kevin Brown | Dustin Hermanson | Kevin Brown | Tim Worrell | 699 | 611 | 88 |
| 2003-09-20 | @ LAN | 153 | W 6-0 | 95-58 | 1 | 54,488 | Kirk Rueter | Hideo Nomo | Kirk Rueter | Hideo Nomo | | 705 | 611 | 94 |
| 2003-09-21 | @ LAN | 154 | L 5-7 | 95-59 | 1 | 54,584 | Kevin Correia | Kazuhisa Ishii | Paul Quantrill | Jim Brower | Eric Gagne | 710 | 618 | 92 |
| 2003-09-22 | @ HOU | 155 | W 6-3 | 96-59 | 1 | 36,372 | Jerome Williams | Ron Villone | Joe Nathan | Billy Wagner | Tim Worrell | 716 | 621 | 95 |
| 2003-09-23 | @ HOU | 156 | W 10-3 | 97-59 | 1 | 36,390 | Jason Schmidt | Wade Miller | Jason Schmidt | Wade Miller | | 726 | 624 | 102 |
| 2003-09-24 | @ HOU | 157 | L 1-2 | 97-60 | 1 | 31,525 | Sidney Ponson | Roy Oswalt | Roy Oswalt | Sidney Ponson | Billy Wagner | 727 | 626 | 101 |
| 2003-09-26 | vs LAN | 158 | W 10-1 | 98-60 | 1 | 42,336 | Kirk Rueter | Kazuhisa Ishii | Kirk Rueter | Kazuhisa Ishii | | 737 | 627 | 110 |
| 2003-09-27 | vs LAN | 159 | L 0-5 | 99-61 | 1 | 42,192 | Jerome Williams | Edwin Jackson | Edwin Jackson | Jerome Williams | | 737 | 632 | 105 |
| 2003-09-27 | vs LAN | 160 | W 6-3 | 99-61 | 1 | 42,485 | Dustin Hermanson | Masao Kida | Joe Nathan | Guillermo Mota | Tim Worrell | 743 | 635 | 108 |
| 2003-09-28 | vs LAN | 161 | W 12-3 | 100-61 | 1 | 42,142 | Kevin Correia | Wilson Alvarez | Kevin Correia | Wilson Alvarez | | 755 | 638 | 117 |