| 2003-03-31 | vs CHA | 1 | W 3-0 | 1-0 | 1 | 40,302 | Runelvys Hernandez | Mark Buehrle | Runelvys Hernandez | Mark Buehrle | Mike MacDougal | 3 | 0 | 3 |
| 2003-04-02 | vs CHA | 2 | W 5-4 | 2-0 | 1 | 10,429 | Jeremy Affeldt | Bartolo Colon | Albie Lopez | Rick White | Mike MacDougal | 8 | 4 | 4 |
| 2003-04-03 | vs CHA | 3 | W 12-6 | 3-0 | 1 | 9,524 | Miguel Asencio | Jon Garland | Ryan Bukvich | Tom Gordon | | 20 | 10 | 10 |
| 2003-04-04 | vs CLE | 4 | W 5-1 | 4-0 | 1 | 15,241 | Chris George | Jason Davis | Chris George | Jason Davis | | 25 | 11 | 14 |
| 2003-04-05 | vs CLE | 5 | W 3-1 | 5-0 | 1 | 19,912 | Runelvys Hernandez | CC Sabathia | Runelvys Hernandez | CC Sabathia | Mike MacDougal | 28 | 12 | 16 |
| 2003-04-09 | @ DET | 6 | W 9-6 | 6-0 | 1 | 14,286 | Jeremy Affeldt | Jeremy Bonderman | Jeremy Affeldt | Jeremy Bonderman | Mike MacDougal | 37 | 18 | 19 |
| 2003-04-10 | @ DET | 7 | W 4-2 | 7-0 | 1 | 9,080 | Miguel Asencio | Mike Maroth | Miguel Asencio | Mike Maroth | Mike MacDougal | 41 | 20 | 21 |
| 2003-04-11 | @ CLE | 8 | W 1-0 | 8-0 | 1 | 17,931 | Runelvys Hernandez | Jake Westbrook | Runelvys Hernandez | Jake Westbrook | Mike MacDougal | 42 | 20 | 22 |
| 2003-04-12 | @ CLE | 9 | W 5-2 | 9-0 | 1 | 18,168 | Chris George | CC Sabathia | Chris George | CC Sabathia | D.J. Carrasco | 47 | 22 | 25 |
| 2003-04-13 | @ CLE | 10 | L 1-6 | 9-1 | 1 | 19,335 | Darrell May | Ricardo Rodriguez | Ricardo Rodriguez | Darrell May | | 48 | 28 | 20 |
| 2003-04-14 | @ CLE | 11 | W 12-4 | 10-1 | 1 | 15,875 | Jeremy Affeldt | Brian Anderson | Jeremy Affeldt | Brian Anderson | | 60 | 32 | 28 |
| 2003-04-15 | @ CHA | 12 | W 8-5 | 11-1 | 1 | 20,591 | Miguel Asencio | Mark Buehrle | Albie Lopez | Billy Koch | Mike MacDougal | 68 | 37 | 31 |
| 2003-04-16 | @ CHA | 13 | L 3-4 | 11-2 | 1 | 9,882 | Runelvys Hernandez | Jon Garland | Tom Gordon | Jason Grimsley | | 71 | 41 | 30 |
| 2003-04-17 | @ CHA | 14 | L 2-8 | 11-3 | 1 | 10,716 | Chris George | Esteban Loaiza | Esteban Loaiza | Chris George | | 73 | 49 | 24 |
| 2003-04-18 | vs DET | 15 | W 4-3 | 12-3 | 1 | 38,937 | Darrell May | Nate Cornejo | D.J. Carrasco | Matt Anderson | | 77 | 52 | 25 |
| 2003-04-19 | vs DET | 16 | W 9-2 | 13-3 | 1 | 13,777 | Jeremy Affeldt | Gary Knotts | Albie Lopez | Gary Knotts | | 86 | 54 | 32 |
| 2003-04-20 | vs DET | 17 | W 4-3 | 14-3 | 1 | 16,203 | Miguel Asencio | Mike Maroth | Mike MacDougal | Mike Maroth | | 90 | 57 | 33 |
| 2003-04-22 | vs MIN | 18 | W 4-3 | 15-3 | 1 | 17,439 | Runelvys Hernandez | Kenny Rogers | Runelvys Hernandez | Kenny Rogers | Mike MacDougal | 94 | 60 | 34 |
| 2003-04-24 | vs MIN | 19 | W 2-1 | 16-3 | 1 | 11,981 | Chris George | Brad Radke | Chris George | Brad Radke | Mike MacDougal | 96 | 61 | 35 |
| 2003-04-25 | @ TOR | 20 | L 5-6 | 16-4 | 1 | 16,417 | Darrell May | Roy Halladay | Kelvim Escobar | D.J. Carrasco | | 101 | 67 | 34 |
| 2003-04-26 | @ TOR | 21 | W 9-6 | 17-4 | 1 | 17,197 | Miguel Asencio | Cory Lidle | Jason Grimsley | Jeff Tam | Mike MacDougal | 110 | 73 | 37 |
| 2003-04-27 | @ TOR | 22 | L 9-10 | 17-5 | 1 | 17,059 | Runelvys Hernandez | Pete Walker | Cliff Politte | Mike MacDougal | | 119 | 83 | 36 |
| 2003-04-29 | @ BOS | 23 | L 2-7 | 17-6 | 1 | 30,438 | Chris George | Tim Wakefield | Tim Wakefield | Chris George | | 121 | 90 | 31 |
| 2003-04-30 | @ BOS | 24 | L 4-5 | 17-7 | 1 | 31,334 | Darrell May | Derek Lowe | Alan Embree | Mike MacDougal | | 125 | 95 | 30 |
| 2003-05-01 | @ BOS | 25 | L 5-6 | 17-8 | 1 | 31,950 | Kyle Snyder | Casey Fossum | Jason Shiell | Jason Grimsley | Brandon Lyon | 130 | 101 | 29 |
| 2003-05-02 | @ BAL | 26 | W 5-2 | 18-8 | 1 | 26,737 | Miguel Asencio | Rick Helling | Miguel Asencio | Rick Helling | | 135 | 103 | 32 |
| 2003-05-03 | @ BAL | 27 | L 1-6 | 18-9 | 1 | 27,866 | Runelvys Hernandez | Sidney Ponson | Sidney Ponson | Runelvys Hernandez | | 136 | 109 | 27 |
| 2003-05-04 | @ BAL | 28 | W 4-0 | 19-9 | 1 | 26,890 | Chris George | Eric DuBose | Chris George | Eric DuBose | D.J. Carrasco | 140 | 109 | 31 |
| 2003-05-05 | vs BOS | 29 | W 7-6 | 20-9 | 1 | 21,232 | Darrell May | Derek Lowe | Albie Lopez | Brandon Lyon | | 147 | 115 | 32 |
| 2003-05-06 | vs BOS | 30 | L 3-7 | 20-10 | 1 | 15,848 | Jeremy Affeldt | Casey Fossum | Casey Fossum | Jeremy Affeldt | | 150 | 122 | 28 |
| 2003-05-07 | vs BOS | 31 | L 6-9 | 20-11 | 1 | 28,268 | Kyle Snyder | John Burkett | Steve Woodard | Albie Lopez | Brandon Lyon | 156 | 131 | 25 |
| 2003-05-09 | vs BAL | 32 | L 5-15 | 20-13 | 1 | 0 | Miguel Asencio | Rick Helling | Rick Helling | Miguel Asencio | | 161 | 146 | 15 |
| 2003-05-09 | vs BAL | 33 | L 4-5 | 20-13 | 1 | 38,995 | Runelvys Hernandez | Sidney Ponson | Sidney Ponson | Runelvys Hernandez | Jorge Julio | 165 | 151 | 14 |
| 2003-05-10 | vs BAL | 34 | W 8-4 | 21-13 | 1 | 25,930 | Chris George | Jason Johnson | D.J. Carrasco | Buddy Groom | | 173 | 155 | 18 |
| 2003-05-11 | vs BAL | 35 | W 8-5 | 22-13 | 1 | 16,105 | Darrell May | Pat Hentgen | Sean Lowe | Travis Driskill | | 181 | 160 | 21 |
| 2003-05-12 | @ MIN | 36 | W 3-2 | 23-13 | 1 | 12,199 | Jeremy Affeldt | Joe Mays | Jeremy Affeldt | Joe Mays | Mike MacDougal | 184 | 162 | 22 |
| 2003-05-13 | @ MIN | 37 | L 2-4 | 23-14 | 1 | 13,898 | Kyle Snyder | Kyle Lohse | LaTroy Hawkins | Albie Lopez | | 186 | 166 | 20 |
| 2003-05-14 | @ MIN | 38 | L 0-7 | 23-15 | 1 | 15,148 | Runelvys Hernandez | Rick Reed | Rick Reed | Runelvys Hernandez | | 186 | 173 | 13 |
| 2003-05-15 | @ MIN | 39 | W 9-5 | 24-15 | 1 | 17,219 | Miguel Asencio | Kenny Rogers | D.J. Carrasco | Johan Santana | | 195 | 178 | 17 |
| 2003-05-16 | vs TOR | 40 | L 1-18 | 24-16 | 1 | 24,167 | Chris George | Mark Hendrickson | Mark Hendrickson | Chris George | | 196 | 196 | 0 |
| 2003-05-17 | vs TOR | 41 | L 4-7 | 24-17 | 1 | 25,032 | Jeremy Affeldt | Roy Halladay | Roy Halladay | Jason Grimsley | Cliff Politte | 200 | 203 | -3 |
| 2003-05-18 | vs TOR | 42 | L 3-4 | 24-18 | 2 | 15,462 | Kyle Snyder | Kelvim Escobar | Tanyon Sturtze | Kyle Snyder | Cliff Politte | 203 | 207 | -4 |
| 2003-05-20 | @ SEA | 43 | L 4-7 | 24-19 | 2 | 36,423 | Darrell May | Ryan Franklin | Jeff Nelson | D.J. Carrasco | | 207 | 214 | -7 |
| 2003-05-21 | @ SEA | 44 | W 14-5 | 25-19 | 2 | 31,251 | Chris George | Freddy Garcia | Chris George | Freddy Garcia | | 221 | 219 | 2 |
| 2003-05-22 | @ SEA | 45 | L 1-5 | 25-20 | 2 | 38,322 | Jeremy Affeldt | Gil Meche | Gil Meche | Jeremy Affeldt | | 222 | 224 | -2 |
| 2003-05-23 | @ OAK | 46 | L 1-4 | 25-21 | 2 | 32,682 | Kyle Snyder | Mark Mulder | Mark Mulder | Kyle Snyder | | 223 | 228 | -5 |
| 2003-05-24 | @ OAK | 47 | W 3-1 | 26-21 | 2 | 24,099 | Kris Wilson | Ted Lilly | Kris Wilson | Ted Lilly | Mike MacDougal | 226 | 229 | -3 |
| 2003-05-25 | @ OAK | 48 | L 3-4 | 26-22 | 2 | 37,705 | Darrell May | Tim Hudson | Keith Foulke | D.J. Carrasco | | 229 | 233 | -4 |
| 2003-05-27 | vs SEA | 49 | L 7-15 | 26-23 | 2 | 14,154 | Chris George | Freddy Garcia | Freddy Garcia | Chris George | | 236 | 248 | -12 |
| 2003-05-28 | vs SEA | 50 | L 2-5 | 26-24 | 2 | 14,928 | Jeremy Affeldt | Jamie Moyer | Jamie Moyer | Jeremy Affeldt | Kazuhiro Sasaki | 238 | 253 | -15 |
| 2003-05-29 | vs OAK | 51 | L 1-6 | 26-25 | 2 | 15,259 | Kyle Snyder | Mark Mulder | Mark Mulder | Kyle Snyder | | 239 | 259 | -20 |
| 2003-05-30 | vs OAK | 52 | W 11-6 | 27-25 | 2 | 22,172 | Kris Wilson | Tim Hudson | Kris Wilson | Tim Hudson | | 250 | 265 | -15 |
| 2003-05-31 | vs OAK | 53 | L 6-7 | 27-26 | 2 | 31,650 | Darrell May | Ted Lilly | Jim Mecir | Mike MacDougal | Keith Foulke | 256 | 272 | -16 |
| 2003-06-01 | vs OAK | 54 | L 4-6 | 27-27 | 2 | 16,249 | Chris George | Barry Zito | Chad Bradford | Rick DeHart | Keith Foulke | 260 | 278 | -18 |
| 2003-06-03 | @ LAN | 55 | L 3-4 | 27-28 | 2 | 26,409 | Jeremy Affeldt | Odalis Perez | Eric Gagne | D.J. Carrasco | | 263 | 282 | -19 |
| 2003-06-04 | @ LAN | 56 | W 2-1 | 28-28 | 2 | 23,677 | Kyle Snyder | Hideo Nomo | Kyle Snyder | Hideo Nomo | Mike MacDougal | 265 | 283 | -18 |
| 2003-06-05 | @ LAN | 57 | L 2-5 | 28-29 | 2 | 29,170 | Darrell May | Kevin Brown | Kevin Brown | Darrell May | Eric Gagne | 267 | 288 | -21 |
| 2003-06-07 | @ COL | 58 | W 13-11 | 30-29 | 2 | 25,421 | Chris George | Shawn Chacon | Chris George | Shawn Chacon | Mike MacDougal | 280 | 299 | -19 |
| 2003-06-07 | @ COL | 59 | W 9-5 | 30-29 | 2 | 26,435 | D.J. Carrasco | Todd Jones | Jason Gilfillan | Todd Jones | | 289 | 304 | -15 |
| 2003-06-08 | @ COL | 60 | L 7-8 | 30-30 | 2 | 30,084 | Jeremy Affeldt | Scott Elarton | Scott Elarton | Rick DeHart | Jose Jimenez | 296 | 312 | -16 |
| 2003-06-10 | vs ARI | 61 | W 7-3 | 31-30 | 2 | 16,772 | Kyle Snyder | Elmer Dessens | Jason Grimsley | Eddie Oropesa | | 303 | 315 | -12 |
| 2003-06-11 | vs ARI | 62 | L 3-4 | 31-31 | 2 | 15,165 | Darrell May | Andrew Good | Andrew Good | Darrell May | Jose Valverde | 306 | 319 | -13 |
| 2003-06-13 | vs SFN | 63 | W 6-1 | 32-31 | 2 | 31,426 | Chris George | Jason Schmidt | Chris George | Jason Schmidt | | 312 | 320 | -8 |
| 2003-06-14 | vs SFN | 64 | L 4-7 | 32-32 | 2 | 38,261 | D.J. Carrasco | Damian Moss | Damian Moss | Les Walrond | | 316 | 327 | -11 |
| 2003-06-15 | vs SFN | 65 | W 5-4 | 33-32 | 2 | 29,631 | Jose Lima | Jerome Williams | Mike MacDougal | Tim Worrell | | 321 | 331 | -10 |
| 2003-06-16 | vs MIN | 66 | W 9-8 | 34-32 | 2 | 13,442 | Darrell May | Kyle Lohse | Mike MacDougal | Eddie Guardado | | 330 | 339 | -9 |
| 2003-06-17 | vs MIN | 67 | W 14-7 | 35-32 | 2 | 16,359 | Jeremy Affeldt | Kenny Rogers | Kris Wilson | Kenny Rogers | | 344 | 346 | -2 |
| 2003-06-18 | vs MIN | 68 | W 8-6 | 36-32 | 2 | 21,581 | Chris George | Rick Reed | Chris George | Rick Reed | Mike MacDougal | 352 | 352 | 0 |
| 2003-06-19 | vs MIN | 69 | L 2-16 | 36-33 | 2 | 22,559 | Kyle Snyder | Joe Mays | Joe Mays | Kyle Snyder | | 354 | 368 | -14 |
| 2003-06-20 | @ SLN | 70 | W 10-4 | 37-33 | 2 | 38,226 | Jose Lima | Matt Morris | Jose Lima | Matt Morris | | 364 | 372 | -8 |
| 2003-06-21 | @ SLN | 71 | L 1-8 | 37-34 | 2 | 44,473 | Darrell May | Woody Williams | Woody Williams | Darrell May | | 365 | 380 | -15 |
| 2003-06-22 | @ SLN | 72 | W 5-2 | 38-34 | 2 | 39,962 | Jeremy Affeldt | Garrett Stephenson | Jeremy Affeldt | Garrett Stephenson | Mike MacDougal | 370 | 382 | -12 |
| 2003-06-24 | @ CLE | 73 | W 3-1 | 39-34 | 1 | 19,638 | Chris George | Jason Davis | Chris George | Jason Davis | Mike MacDougal | 373 | 383 | -10 |
| 2003-06-25 | @ CLE | 74 | W 3-1 | 40-34 | 1 | 18,527 | Kyle Snyder | Brian Anderson | Jason Gilfillan | David Riske | Mike MacDougal | 376 | 384 | -8 |
| 2003-06-26 | @ CLE | 75 | W 4-1 | 41-34 | 1 | 17,494 | Jose Lima | Ricardo Rodriguez | Jose Lima | Ricardo Rodriguez | Mike MacDougal | 380 | 385 | -5 |
| 2003-06-27 | vs SLN | 76 | W 6-3 | 42-34 | 1 | 40,189 | Darrell May | Garrett Stephenson | Darrell May | Garrett Stephenson | Mike MacDougal | 386 | 388 | -2 |
| 2003-06-28 | vs SLN | 77 | L 9-13 | 42-35 | 1 | 40,347 | Jeremy Affeldt | Jason Simontacchi | Jeff Fassero | Jeremy Affeldt | | 395 | 401 | -6 |
| 2003-06-29 | vs SLN | 78 | L 6-13 | 42-36 | 1 | 38,270 | Chris George | Brett Tomko | Brett Tomko | Chris George | | 401 | 414 | -13 |
| 2003-06-30 | vs CLE | 79 | L 5-10 | 42-38 | 2 | 0 | Brad Voyles | Cliff Lee | Cliff Lee | Brad Voyles | | 406 | 424 | -18 |
| 2003-06-30 | vs CLE | 80 | L 5-8 | 42-38 | 2 | 14,645 | Kyle Snyder | Brian Anderson | Brian Anderson | Les Walrond | Danys Baez | 411 | 432 | -21 |
| 2003-07-01 | vs CLE | 81 | W 6-3 | 43-38 | 1 | 12,831 | Jose Lima | Ricardo Rodriguez | Jose Lima | Ricardo Rodriguez | Mike MacDougal | 417 | 435 | -18 |
| 2003-07-02 | vs CLE | 82 | W 8-2 | 44-38 | 1 | 12,918 | Darrell May | Billy Traber | Darrell May | Billy Traber | | 425 | 437 | -12 |
| 2003-07-03 | vs DET | 83 | W 3-2 | 45-38 | 1 | 12,978 | Jeremy Affeldt | Jeremy Bonderman | Jeremy Affeldt | Jeremy Bonderman | Mike MacDougal | 428 | 439 | -11 |
| 2003-07-04 | vs DET | 84 | W 9-8 | 46-38 | 1 | 39,920 | Chris George | Nate Cornejo | Nate Field | Nate Cornejo | Mike MacDougal | 437 | 447 | -10 |
| 2003-07-05 | vs DET | 85 | L 5-9 | 46-39 | 1 | 19,030 | Brad Voyles | Mike Maroth | Mike Maroth | Brad Voyles | Jamie Walker | 442 | 456 | -14 |
| 2003-07-06 | vs DET | 86 | W 5-3 | 47-39 | 1 | 12,844 | Jose Lima | Matt Roney | Jose Lima | Matt Roney | Mike MacDougal | 447 | 459 | -12 |
| 2003-07-08 | @ ANA | 87 | W 4-0 | 48-39 | 1 | 34,283 | Darrell May | John Lackey | Darrell May | John Lackey | | 451 | 459 | -8 |
| 2003-07-09 | @ ANA | 88 | L 3-5 | 48-40 | 1 | 34,196 | Jeremy Affeldt | Kevin Appier | Francisco Rodriguez | Jeremy Affeldt | Troy Percival | 454 | 464 | -10 |
| 2003-07-10 | @ ANA | 89 | L 1-7 | 48-41 | 1 | 38,836 | Chris George | Aaron Sele | Aaron Sele | Chris George | | 455 | 471 | -16 |
| 2003-07-11 | @ TEX | 90 | W 13-3 | 49-41 | 1 | 33,536 | Runelvys Hernandez | R.A. Dickey | Kris Wilson | R.A. Dickey | | 468 | 474 | -6 |
| 2003-07-12 | @ TEX | 91 | W 8-2 | 50-41 | 1 | 32,654 | Jose Lima | Ismael Valdez | Jose Lima | Ismael Valdez | | 476 | 476 | 0 |
| 2003-07-13 | @ TEX | 92 | W 8-2 | 51-41 | 1 | 21,424 | Darrell May | Tony Mounce | Darrell May | Tony Mounce | | 484 | 478 | 6 |
| 2003-07-17 | vs SEA | 93 | W 7-1 | 52-41 | 1 | 22,481 | Jose Lima | Freddy Garcia | Jose Lima | Freddy Garcia | | 491 | 479 | 12 |
| 2003-07-18 | vs SEA | 94 | L 3-6 | 52-42 | 1 | 30,698 | Jeremy Affeldt | Ryan Franklin | Arthur Rhodes | Mike MacDougal | Shigetoshi Hasegawa | 494 | 485 | 9 |
| 2003-07-19 | vs SEA | 95 | W 5-1 | 53-42 | 1 | 39,808 | Darrell May | Gil Meche | Darrell May | Gil Meche | | 499 | 486 | 13 |
| 2003-07-20 | vs SEA | 96 | W 7-5 | 54-42 | 1 | 16,880 | Runelvys Hernandez | Jamie Moyer | Kris Wilson | Arthur Rhodes | | 506 | 491 | 15 |
| 2003-07-21 | vs OAK | 97 | L 1-6 | 54-43 | 1 | 22,627 | Kyle Snyder | Rich Harden | Ricardo Rincon | Sean Lowe | | 507 | 497 | 10 |
| 2003-07-22 | vs OAK | 98 | L 0-10 | 54-44 | 1 | 23,500 | Kris Wilson | Tim Hudson | Tim Hudson | Kris Wilson | | 507 | 507 | 0 |
| 2003-07-23 | @ MIN | 99 | W 8-3 | 55-44 | 1 | 24,193 | Jeremy Affeldt | Johan Santana | Jeremy Affeldt | Johan Santana | | 515 | 510 | 5 |
| 2003-07-24 | @ MIN | 100 | L 2-6 | 55-45 | 1 | 29,687 | Darrell May | Brad Radke | LaTroy Hawkins | Jason Grimsley | | 517 | 516 | 1 |
| 2003-07-25 | @ DET | 101 | W 8-3 | 56-45 | 1 | 29,697 | Runelvys Hernandez | Wil Ledezma | Runelvys Hernandez | Wil Ledezma | | 525 | 519 | 6 |
| 2003-07-26 | @ DET | 102 | L 1-5 | 56-46 | 1 | 24,664 | Kyle Snyder | Jeremy Bonderman | Jeremy Bonderman | Kyle Snyder | | 526 | 524 | 2 |
| 2003-07-27 | @ DET | 103 | W 5-1 | 57-46 | 1 | 35,326 | Jose Lima | Mike Maroth | Jose Lima | Mike Maroth | | 531 | 525 | 6 |
| 2003-07-29 | vs CHA | 104 | L 6-9 | 57-47 | 1 | 24,485 | Darrell May | Mark Buehrle | Mark Buehrle | Darrell May | Tom Gordon | 537 | 534 | 3 |
| 2003-07-30 | vs CHA | 105 | L 4-15 | 57-48 | 1 | 20,722 | Runelvys Hernandez | Jon Garland | Jon Garland | Runelvys Hernandez | | 541 | 549 | -8 |
| 2003-07-31 | vs CHA | 106 | L 6-8 | 57-49 | 1 | 21,352 | Kyle Snyder | Esteban Loaiza | Scott Schoeneweis | Nate Field | | 547 | 557 | -10 |
| 2003-08-01 | vs TBA | 107 | L 6-9 | 57-50 | 1 | 33,379 | Jose Lima | Joe Kennedy | Brandon Backe | Graeme Lloyd | Lance Carter | 553 | 566 | -13 |
| 2003-08-02 | vs TBA | 108 | W 10-8 | 58-50 | 1 | 38,709 | Darrell May | Rob Bell | Curt Leskanic | Mark Malaska | Mike MacDougal | 563 | 574 | -11 |
| 2003-08-03 | vs TBA | 109 | W 2-0 | 59-50 | 1 | 15,870 | Jimmy Gobble | Geremi Gonzalez | Jimmy Gobble | Geremi Gonzalez | Jeremy Affeldt | 565 | 574 | -9 |
| 2003-08-04 | @ CHA | 110 | W 13-9 | 60-50 | 1 | 43,922 | Runelvys Hernandez | Jon Garland | Runelvys Hernandez | Scott Schoeneweis | Al Levine | 578 | 583 | -5 |
| 2003-08-05 | @ CHA | 111 | L 4-5 | 60-51 | 1 | 38,973 | Kyle Snyder | Esteban Loaiza | Esteban Loaiza | Kyle Snyder | Damaso Marte | 582 | 588 | -6 |
| 2003-08-06 | @ CHA | 112 | L 3-4 | 60-52 | 1 | 25,348 | Kris Wilson | Bartolo Colon | Bartolo Colon | Kris Wilson | Damaso Marte | 585 | 592 | -7 |
| 2003-08-07 | @ TBA | 113 | L 2-3 | 60-53 | 1 | 8,834 | Darrell May | Rob Bell | Chad Gaudin | Mike MacDougal | | 587 | 595 | -8 |
| 2003-08-08 | @ TBA | 114 | L 0-4 | 60-54 | 2 | 9,381 | Kevin Appier | Geremi Gonzalez | Geremi Gonzalez | Kevin Appier | | 587 | 599 | -12 |
| 2003-08-09 | @ TBA | 115 | W 6-2 | 61-54 | 1 | 15,975 | Jimmy Gobble | Victor Zambrano | Jimmy Gobble | Victor Zambrano | | 593 | 601 | -8 |
| 2003-08-10 | @ TBA | 116 | W 7-3 | 62-54 | 1 | 11,327 | Runelvys Hernandez | Jorge Sosa | Runelvys Hernandez | Jorge Sosa | | 600 | 604 | -4 |
| 2003-08-11 | vs NYA | 117 | W 12-9 | 63-54 | 1 | 40,406 | Paul Abbott | David Wells | D.J. Carrasco | Sterling Hitchcock | | 612 | 613 | -1 |
| 2003-08-12 | vs NYA | 118 | L 0-6 | 63-55 | 1 | 37,820 | Darrell May | Mike Mussina | Mike Mussina | Darrell May | | 612 | 619 | -7 |
| 2003-08-13 | vs NYA | 119 | W 11-0 | 64-55 | 1 | 35,596 | Kevin Appier | Jeff Weaver | Kevin Appier | Jeff Weaver | | 623 | 619 | 4 |
| 2003-08-15 | vs MIN | 120 | L 2-9 | 64-56 | 1 | 39,927 | Jimmy Gobble | Kenny Rogers | Kenny Rogers | Jimmy Gobble | | 625 | 628 | -3 |
| 2003-08-16 | vs MIN | 121 | L 5-14 | 64-57 | 1 | 28,994 | Runelvys Hernandez | Kyle Lohse | Kyle Lohse | Runelvys Hernandez | | 630 | 642 | -12 |
| 2003-08-17 | vs MIN | 122 | W 5-4 | 65-57 | 1 | 18,875 | Darrell May | Rick Reed | Darrell May | Rick Reed | Curt Leskanic | 635 | 646 | -11 |
| 2003-08-18 | @ NYA | 123 | L 6-11 | 65-58 | 1 | 48,937 | Jose Lima | Jeff Weaver | Jeff Weaver | Jose Lima | | 641 | 657 | -16 |
| 2003-08-19 | @ NYA | 124 | L 3-6 | 65-59 | 1 | 43,841 | Kevin Appier | Andy Pettitte | Andy Pettitte | Kevin Appier | Mariano Rivera | 644 | 663 | -19 |
| 2003-08-20 | @ NYA | 125 | L 7-8 | 65-60 | 1 | 46,973 | Jimmy Gobble | Roger Clemens | Roger Clemens | Jimmy Gobble | Mariano Rivera | 651 | 671 | -20 |
| 2003-08-21 | @ MIN | 126 | L 3-4 | 65-61 | 3 | 30,179 | Paul Abbott | Kenny Rogers | Kenny Rogers | Al Levine | Eddie Guardado | 654 | 675 | -21 |
| 2003-08-22 | @ MIN | 127 | W 3-2 | 66-61 | 2 | 36,101 | Darrell May | Kyle Lohse | Darrell May | Kyle Lohse | Jeremy Affeldt | 657 | 677 | -20 |
| 2003-08-23 | @ MIN | 128 | W 4-3 | 67-61 | 2 | 37,782 | Jose Lima | Joe Mays | D.J. Carrasco | Joe Mays | Mike MacDougal | 661 | 680 | -19 |
| 2003-08-24 | @ MIN | 129 | L 1-8 | 67-62 | 2 | 34,265 | Kevin Appier | Johan Santana | Johan Santana | Graeme Lloyd | | 662 | 688 | -26 |
| 2003-08-26 | vs TEX | 130 | W 9-2 | 68-62 | 2 | 12,917 | Brian Anderson | R.A. Dickey | Brian Anderson | R.A. Dickey | | 671 | 690 | -19 |
| 2003-08-27 | vs TEX | 131 | W 9-0 | 69-62 | 2 | 12,462 | Darrell May | Colby Lewis | Darrell May | Colby Lewis | | 680 | 690 | -10 |
| 2003-08-28 | vs TEX | 132 | W 6-5 | 70-62 | 1 | 11,944 | Paul Abbott | Ismael Valdez | D.J. Carrasco | Erasmo Ramirez | | 686 | 695 | -9 |
| 2003-08-29 | vs ANA | 133 | L 3-10 | 70-63 | 1 | 23,836 | Jimmy Gobble | Jarrod Washburn | Jarrod Washburn | Jimmy Gobble | | 689 | 705 | -16 |
| 2003-08-31 | vs ANA | 134 | L 4-7 | 70-64 | 2 | 21,324 | Brian Anderson | Scot Shields | Scot Shields | Brian Anderson | Troy Percival | 693 | 712 | -19 |
| 2003-09-01 | @ TEX | 135 | L 3-7 | 70-65 | 2 | 24,005 | Darrell May | Colby Lewis | Colby Lewis | Darrell May | | 696 | 719 | -23 |
| 2003-09-02 | @ TEX | 136 | L 7-8 | 70-66 | 3 | 15,119 | Paul Abbott | Ismael Valdez | Ismael Valdez | Jeremy Affeldt | Francisco Cordero | 703 | 727 | -24 |
| 2003-09-03 | @ TEX | 137 | W 3-1 | 71-66 | 3 | 15,271 | Jimmy Gobble | John Thomson | Jimmy Gobble | John Thomson | Mike MacDougal | 706 | 728 | -22 |
| 2003-09-04 | vs ARI | 138 | L 5-6 | 71-67 | 3 | 20,385 | Brad Voyles | Randy Johnson | Matt Mantei | Kris Wilson | | 711 | 734 | -23 |
| 2003-09-05 | @ ANA | 139 | W 5-0 | 72-67 | 3 | 43,111 | Brian Anderson | Jarrod Washburn | Brian Anderson | Jarrod Washburn | | 716 | 734 | -18 |
| 2003-09-06 | @ ANA | 140 | L 5-6 | 72-69 | 3 | 0 | Darrell May | Scot Shields | Ben Weber | Jason Grimsley | Troy Percival | 721 | 740 | -19 |
| 2003-09-06 | @ ANA | 141 | L 1-3 | 72-69 | 3 | 43,044 | Jamey Wright | Kevin Gregg | Kevin Gregg | Jamey Wright | Troy Percival | 722 | 743 | -21 |
| 2003-09-07 | @ ANA | 142 | W 3-0 | 73-69 | 3 | 38,943 | Paul Abbott | John Lackey | Paul Abbott | John Lackey | Jeremy Affeldt | 725 | 743 | -18 |
| 2003-09-09 | vs CLE | 143 | L 1-7 | 73-70 | 3 | 12,389 | Jimmy Gobble | Jason Davis | Jason Davis | Jimmy Gobble | | 726 | 750 | -24 |
| 2003-09-10 | vs CLE | 144 | W 9-7 | 74-70 | 3 | 21,581 | Brian Anderson | Chad Durbin | Kris Wilson | Jose Santiago | Jeremy Affeldt | 735 | 757 | -22 |
| 2003-09-11 | vs CLE | 145 | L 5-6 | 74-71 | 3 | 13,188 | Darrell May | Jake Westbrook | Danys Baez | Jason Grimsley | David Riske | 740 | 763 | -23 |
| 2003-09-12 | @ DET | 146 | L 0-3 | 74-72 | 3 | 18,042 | Paul Abbott | Mike Maroth | Mike Maroth | Paul Abbott | Fernando Rodney | 740 | 766 | -26 |
| 2003-09-13 | @ DET | 147 | W 7-0 | 75-72 | 3 | 15,966 | Jamey Wright | Chris Mears | Jamey Wright | Chris Mears | | 747 | 766 | -19 |
| 2003-09-14 | @ DET | 148 | W 7-2 | 76-72 | 3 | 13,579 | Jimmy Gobble | Nate Robertson | Jimmy Gobble | Nate Robertson | | 754 | 768 | -14 |
| 2003-09-15 | @ DET | 149 | W 10-4 | 77-72 | 3 | 9,342 | Brian Anderson | Gary Knotts | Brian Anderson | Gary Knotts | | 764 | 772 | -8 |
| 2003-09-16 | @ CLE | 150 | W 12-8 | 78-72 | 3 | 16,145 | Darrell May | Billy Traber | Darrell May | Billy Traber | | 776 | 780 | -4 |
| 2003-09-17 | @ CLE | 151 | L 1-9 | 78-73 | 3 | 16,363 | Paul Abbott | Jake Westbrook | Jake Westbrook | Paul Abbott | | 777 | 789 | -12 |
| 2003-09-18 | @ CLE | 152 | W 3-2 | 79-73 | 3 | 17,275 | Jose Lima | CC Sabathia | Jose Lima | CC Sabathia | Curt Leskanic | 780 | 791 | -11 |
| 2003-09-19 | @ CHA | 153 | L 5-8 | 79-74 | 3 | 32,812 | Jamey Wright | Mark Buehrle | Mark Buehrle | D.J. Carrasco | Tom Gordon | 785 | 799 | -14 |
| 2003-09-20 | @ CHA | 154 | W 7-1 | 80-74 | 3 | 37,367 | Brian Anderson | Esteban Loaiza | Brian Anderson | Esteban Loaiza | | 792 | 800 | -8 |
| 2003-09-21 | @ CHA | 155 | W 10-4 | 81-74 | 3 | 31,539 | Darrell May | Jon Garland | Darrell May | Jon Garland | | 802 | 804 | -2 |
| 2003-09-22 | vs DET | 156 | W 12-6 | 82-74 | 3 | 10,574 | Paul Abbott | Gary Knotts | Jeremy Affeldt | Gary Knotts | | 814 | 810 | 4 |
| 2003-09-23 | vs DET | 157 | L 6-15 | 82-75 | 3 | 11,180 | Jose Lima | Mike Maroth | Mike Maroth | Jose Lima | | 820 | 825 | -5 |
| 2003-09-24 | vs DET | 158 | L 3-4 | 82-76 | 3 | 10,758 | Jimmy Gobble | Shane Loux | Shane Loux | Jimmy Gobble | Fernando Rodney | 823 | 829 | -6 |
| 2003-09-25 | vs CHA | 159 | W 7-3 | 83-76 | 3 | 16,438 | Brian Anderson | Dan Wright | Brian Anderson | Dan Wright | | 830 | 832 | -2 |
| 2003-09-26 | vs CHA | 160 | L 2-11 | 83-77 | 3 | 36,598 | Darrell May | Jon Garland | Jon Garland | Darrell May | | 832 | 843 | -11 |
| 2003-09-27 | vs CHA | 161 | L 3-19 | 83-78 | 3 | 37,567 | Jamey Wright | Bartolo Colon | Bartolo Colon | Jamey Wright | | 835 | 862 | -27 |
| 2003-09-28 | vs CHA | 162 | L 1-5 | 83-79 | 3 | 26,261 | Jose Lima | Esteban Loaiza | Esteban Loaiza | Jose Lima | | 836 | 867 | -31 |