| 2003-03-31 | @ ATL | 1 | W 10-2 | 1-0 | 1 | 40,258 | Tony Armas | Greg Maddux | Tony Armas | Greg Maddux | | 10 | 2 | 8 |
| 2003-04-02 | @ ATL | 2 | W 3-0 | 2-0 | 1 | 19,116 | Zach Day | Horacio Ramirez | Zach Day | Horacio Ramirez | Rocky Biddle | 13 | 2 | 11 |
| 2003-04-03 | @ ATL | 3 | W 4-0 | 3-0 | 1 | 19,505 | Javier Vazquez | Russ Ortiz | Javier Vazquez | Russ Ortiz | | 17 | 2 | 15 |
| 2003-04-04 | @ NYN | 4 | L 0-4 | 3-1 | 1 | 18,040 | Tomo Ohka | David Cone | David Cone | Tomo Ohka | | 17 | 6 | 11 |
| 2003-04-05 | @ NYN | 5 | L 1-3 | 3-2 | 1 | 36,817 | Tony Armas | Tom Glavine | Tom Glavine | Tony Armas | Armando Benitez | 18 | 9 | 9 |
| 2003-04-06 | @ NYN | 6 | W 8-5 | 4-2 | 1 | 35,093 | Livan Hernandez | Jae Weong Seo | Scott Stewart | Armando Benitez | Rocky Biddle | 26 | 14 | 12 |
| 2003-04-08 | @ CHN | 7 | L 1-6 | 4-3 | 1 | 29,138 | Zach Day | Matt Clement | Matt Clement | Zach Day | | 27 | 20 | 7 |
| 2003-04-09 | @ CHN | 8 | L 0-3 | 4-4 | 2 | 29,966 | Javier Vazquez | Mark Prior | Mark Prior | Javier Vazquez | | 27 | 23 | 4 |
| 2003-04-10 | @ CHN | 9 | W 7-1 | 5-4 | 1 | 30,225 | Tony Armas | Shawn Estes | Tony Armas | Shawn Estes | | 34 | 24 | 10 |
| 2003-04-11 | vs NYN | 10 | W 10-0 | 6-4 | 1 | 17,906 | Tomo Ohka | David Cone | Tomo Ohka | David Cone | | 44 | 24 | 20 |
| 2003-04-12 | vs NYN | 11 | W 5-4 | 7-4 | 1 | 18,264 | Livan Hernandez | Jae Weong Seo | Livan Hernandez | Jae Weong Seo | Rocky Biddle | 49 | 28 | 21 |
| 2003-04-13 | vs NYN | 12 | W 2-1 | 8-4 | 1 | 16,332 | Zach Day | Al Leiter | Rocky Biddle | Mike Stanton | | 51 | 29 | 22 |
| 2003-04-14 | vs NYN | 13 | W 5-3 | 9-4 | 1 | 13,155 | Javier Vazquez | Steve Trachsel | Dan Smith | Scott Strickland | Rocky Biddle | 56 | 32 | 24 |
| 2003-04-15 | vs ATL | 14 | L 1-2 | 9-5 | 1 | 13,399 | Tony Armas | Shane Reynolds | Jung Bong | Dan Smith | John Smoltz | 57 | 34 | 23 |
| 2003-04-16 | vs ATL | 15 | L 2-3 | 9-6 | 1 | 15,571 | Tomo Ohka | Horacio Ramirez | Horacio Ramirez | Tomo Ohka | John Smoltz | 59 | 37 | 22 |
| 2003-04-17 | vs ATL | 16 | L 8-14 | 9-7 | 1 | 13,170 | Livan Hernandez | Russ Ortiz | Jung Bong | Rocky Biddle | | 67 | 51 | 16 |
| 2003-04-19 | vs CIN | 17 | W 8-7 | 11-7 | 1 | 10,296 | Zach Day | Ryan Dempster | Luis Ayala | Scott Williamson | | 75 | 58 | 17 |
| 2003-04-19 | vs CIN | 18 | W 9-5 | 11-7 | 1 | 13,109 | Javier Vazquez | Jimmy Anderson | Javier Vazquez | Jimmy Anderson | | 84 | 63 | 21 |
| 2003-04-20 | vs CIN | 19 | L 5-7 | 11-8 | 1 | 11,619 | Tony Armas | Danny Graves | Scott Sullivan | Luis Ayala | Scott Williamson | 89 | 70 | 19 |
| 2003-04-22 | vs ARI | 20 | W 4-0 | 12-8 | 1 | 36,879 | Tomo Ohka | Andrew Good | Tomo Ohka | Andrew Good | | 93 | 70 | 23 |
| 2003-04-23 | vs ARI | 21 | L 2-6 | 12-9 | 2 | 6,380 | Livan Hernandez | Elmer Dessens | Elmer Dessens | Livan Hernandez | | 95 | 76 | 19 |
| 2003-04-24 | vs ARI | 22 | W 1-0 | 13-9 | 2 | 5,954 | Javier Vazquez | Byung-Hyun Kim | Javier Vazquez | Byung-Hyun Kim | Rocky Biddle | 96 | 76 | 20 |
| 2003-04-25 | vs HOU | 23 | W 10-2 | 14-9 | 1 | 6,863 | Zach Day | Jeriome Robertson | Zach Day | Jeriome Robertson | | 106 | 78 | 28 |
| 2003-04-26 | vs HOU | 24 | W 3-2 | 15-9 | 1 | 8,492 | Claudio Vargas | Scott Linebrink | Rocky Biddle | Billy Wagner | | 109 | 80 | 29 |
| 2003-04-27 | vs HOU | 25 | L 3-6 | 15-10 | 2 | 13,310 | Tomo Ohka | Tim Redding | Tim Redding | Tomo Ohka | Octavio Dotel | 112 | 86 | 26 |
| 2003-04-29 | @ MIL | 26 | W 3-2 | 16-10 | 2 | 10,044 | Javier Vazquez | Matt Kinney | Scott Stewart | Mike DeJean | Rocky Biddle | 115 | 88 | 27 |
| 2003-04-30 | @ MIL | 27 | W 9-5 | 17-10 | 2 | 10,945 | Livan Hernandez | Ben Sheets | Livan Hernandez | Ben Sheets | | 124 | 93 | 31 |
| 2003-05-01 | @ MIL | 28 | W 5-0 | 18-10 | 2 | 13,180 | Zach Day | Wayne Franklin | Zach Day | Wayne Franklin | | 129 | 93 | 36 |
| 2003-05-02 | @ SLN | 29 | L 1-8 | 18-11 | 2 | 41,810 | Tomo Ohka | Jason Simontacchi | Jason Simontacchi | Tomo Ohka | | 130 | 101 | 29 |
| 2003-05-03 | @ SLN | 30 | L 1-3 | 18-12 | 2 | 36,176 | Claudio Vargas | Garrett Stephenson | Garrett Stephenson | Claudio Vargas | Kiko Calero | 131 | 104 | 27 |
| 2003-05-04 | @ SLN | 31 | L 2-6 | 18-13 | 3 | 39,605 | Javier Vazquez | Matt Morris | Matt Morris | Javier Vazquez | | 133 | 110 | 23 |
| 2003-05-06 | vs SDN | 32 | W 4-2 | 19-13 | 2 | 5,841 | Livan Hernandez | Jake Peavy | Livan Hernandez | Jake Peavy | Rocky Biddle | 137 | 112 | 25 |
| 2003-05-07 | vs SDN | 33 | W 12-9 | 20-13 | 2 | 5,111 | Zach Day | Clay Condrey | Rocky Biddle | Jesse Orosco | | 149 | 121 | 28 |
| 2003-05-08 | vs SDN | 34 | W 12-5 | 21-13 | 2 | 5,274 | Tomo Ohka | Brian Lawrence | Tomo Ohka | Brian Lawrence | | 161 | 126 | 35 |
| 2003-05-09 | vs LAN | 35 | L 5-9 | 21-14 | 2 | 10,675 | Claudio Vargas | Kevin Brown | Guillermo Mota | Scott Stewart | | 166 | 135 | 31 |
| 2003-05-10 | vs LAN | 36 | W 6-5 | 22-14 | 2 | 8,084 | Javier Vazquez | Darren Dreifort | Luis Ayala | Tom Martin | Rocky Biddle | 172 | 140 | 32 |
| 2003-05-11 | vs LAN | 37 | L 3-4 | 22-15 | 2 | 14,488 | Livan Hernandez | Odalis Perez | Odalis Perez | Livan Hernandez | Eric Gagne | 175 | 144 | 31 |
| 2003-05-12 | @ SFN | 38 | W 4-3 | 23-15 | 2 | 33,071 | Zach Day | Damian Moss | Zach Day | Damian Moss | Rocky Biddle | 179 | 147 | 32 |
| 2003-05-13 | @ SFN | 39 | W 6-4 | 24-15 | 2 | 32,991 | Tomo Ohka | Kurt Ainsworth | Dan Smith | Kurt Ainsworth | Rocky Biddle | 185 | 151 | 34 |
| 2003-05-14 | @ SFN | 40 | W 6-3 | 25-15 | 2 | 38,963 | Claudio Vargas | Jesse Foppert | Claudio Vargas | Jesse Foppert | | 191 | 154 | 37 |
| 2003-05-15 | @ COL | 41 | L 2-4 | 25-16 | 2 | 23,197 | Javier Vazquez | Jason Jennings | Todd Jones | T.J. Tucker | Jose Jimenez | 193 | 158 | 35 |
| 2003-05-16 | @ COL | 42 | W 4-1 | 26-16 | 2 | 27,117 | Livan Hernandez | Aaron Cook | Luis Ayala | Nelson Cruz | Rocky Biddle | 197 | 159 | 38 |
| 2003-05-17 | @ COL | 43 | W 6-4 | 27-16 | 2 | 30,052 | Zach Day | Jason Young | Luis Ayala | Todd Jones | Rocky Biddle | 203 | 163 | 40 |
| 2003-05-18 | @ COL | 44 | L 0-4 | 27-17 | 2 | 30,720 | Tomo Ohka | Shawn Chacon | Shawn Chacon | Tomo Ohka | | 203 | 167 | 36 |
| 2003-05-20 | vs FLO | 45 | W 6-4 | 28-17 | 2 | 5,435 | Javier Vazquez | Dontrelle Willis | Javier Vazquez | Dontrelle Willis | Rocky Biddle | 209 | 171 | 38 |
| 2003-05-21 | vs FLO | 46 | W 7-2 | 29-17 | 2 | 5,282 | Claudio Vargas | Carl Pavano | Claudio Vargas | Carl Pavano | | 216 | 173 | 43 |
| 2003-05-22 | vs FLO | 47 | W 8-2 | 30-17 | 2 | 6,249 | Livan Hernandez | Michael Tejera | Livan Hernandez | Michael Tejera | | 224 | 175 | 49 |
| 2003-05-23 | vs PHI | 48 | L 2-4 | 30-18 | 2 | 9,511 | Zach Day | Kevin Millwood | Kevin Millwood | Zach Day | Jose Mesa | 226 | 179 | 47 |
| 2003-05-24 | vs PHI | 49 | W 3-2 | 31-18 | 2 | 33,236 | Tomo Ohka | Brandon Duckworth | Luis Ayala | Carlos Silva | | 229 | 181 | 48 |
| 2003-05-25 | vs PHI | 50 | W 5-3 | 32-18 | 2 | 17,023 | Javier Vazquez | Brett Myers | Javier Vazquez | Brett Myers | Rocky Biddle | 234 | 184 | 50 |
| 2003-05-26 | @ FLO | 51 | L 1-5 | 32-19 | 2 | 8,362 | Claudio Vargas | Carl Pavano | Carl Pavano | Claudio Vargas | | 235 | 189 | 46 |
| 2003-05-28 | @ FLO | 52 | L 3-4 | 32-21 | 2 | 0 | Livan Hernandez | Tommy Phelps | Tommy Phelps | Livan Hernandez | Braden Looper | 238 | 193 | 45 |
| 2003-05-28 | @ FLO | 53 | L 0-6 | 32-21 | 2 | 9,169 | Zach Day | Michael Tejera | Michael Tejera | Zach Day | | 238 | 199 | 39 |
| 2003-05-29 | @ FLO | 54 | W 3-2 | 33-21 | 2 | 9,052 | Tomo Ohka | Brad Penny | Tomo Ohka | Armando Almanza | Rocky Biddle | 241 | 201 | 40 |
| 2003-05-30 | @ PHI | 55 | L 5-12 | 33-22 | 2 | 18,311 | Javier Vazquez | Brandon Duckworth | Rheal Cormier | Javier Vazquez | | 246 | 213 | 33 |
| 2003-06-01 | @ PHI | 56 | L 3-4 | 33-24 | 2 | 0 | Livan Hernandez | Randy Wolf | Randy Wolf | Livan Hernandez | Jose Mesa | 249 | 217 | 32 |
| 2003-06-01 | @ PHI | 57 | L 1-4 | 33-24 | 2 | 36,685 | Claudio Vargas | Brett Myers | Brett Myers | Dan Smith | Jose Mesa | 250 | 221 | 29 |
| 2003-06-03 | vs ANA | 58 | L 4-15 | 33-25 | 2 | 10,034 | Tomo Ohka | Ramon Ortiz | Ramon Ortiz | Tomo Ohka | | 254 | 236 | 18 |
| 2003-06-04 | vs ANA | 59 | L 2-11 | 33-26 | 2 | 10,501 | Sun-Woo Kim | Jarrod Washburn | Jarrod Washburn | Sun-Woo Kim | | 256 | 247 | 9 |
| 2003-06-05 | vs ANA | 60 | W 8-7 | 34-26 | 2 | 10,598 | Javier Vazquez | John Lackey | Joey Eischen | Mickey Callaway | | 264 | 254 | 10 |
| 2003-06-06 | vs TEX | 61 | W 13-10 | 35-26 | 2 | 18,005 | Livan Hernandez | Colby Lewis | Livan Hernandez | Colby Lewis | | 277 | 264 | 13 |
| 2003-06-07 | vs TEX | 62 | W 5-4 | 36-26 | 2 | 18,003 | Claudio Vargas | Chan Ho Park | Claudio Vargas | Brian Shouse | Luis Ayala | 282 | 268 | 14 |
| 2003-06-08 | vs TEX | 63 | W 3-2 | 37-26 | 2 | 18,001 | Tomo Ohka | Ismael Valdez | Scott Stewart | Francisco Cordero | Rocky Biddle | 285 | 270 | 15 |
| 2003-06-10 | @ SEA | 64 | W 7-3 | 38-26 | 2 | 34,811 | Javier Vazquez | Gil Meche | Javier Vazquez | Gil Meche | Luis Ayala | 292 | 273 | 19 |
| 2003-06-11 | @ SEA | 65 | W 3-1 | 39-26 | 2 | 32,853 | Livan Hernandez | Joel Pineiro | Livan Hernandez | Joel Pineiro | Rocky Biddle | 295 | 274 | 21 |
| 2003-06-12 | @ SEA | 66 | L 0-1 | 39-27 | 2 | 33,761 | Claudio Vargas | Ryan Franklin | Ryan Franklin | Claudio Vargas | Arthur Rhodes | 295 | 275 | 20 |
| 2003-06-13 | @ OAK | 67 | L 4-8 | 39-28 | 2 | 14,186 | Tomo Ohka | Mark Mulder | Mark Mulder | Tomo Ohka | | 299 | 283 | 16 |
| 2003-06-14 | @ OAK | 68 | L 4-5 | 39-29 | 2 | 26,447 | T.J. Tucker | Aaron Harang | Ricardo Rincon | Luis Ayala | Keith Foulke | 303 | 288 | 15 |
| 2003-06-15 | @ OAK | 69 | L 1-9 | 39-30 | 2 | 31,024 | Javier Vazquez | Tim Hudson | Tim Hudson | Javier Vazquez | | 304 | 297 | 7 |
| 2003-06-18 | @ PIT | 70 | L 3-7 | 39-32 | 2 | 0 | Livan Hernandez | Jeff D'Amico | Jeff D'Amico | Livan Hernandez | Mike Williams | 307 | 304 | 3 |
| 2003-06-18 | @ PIT | 71 | L 3-4 | 39-32 | 2 | 22,557 | Claudio Vargas | Jeff Suppan | Salomon Torres | Rocky Biddle | | 310 | 308 | 2 |
| 2003-06-19 | @ PIT | 72 | W 5-2 | 40-32 | 2 | 16,050 | Tomo Ohka | Kip Wells | Tomo Ohka | Salomon Torres | Rocky Biddle | 315 | 310 | 5 |
| 2003-06-20 | vs TOR | 73 | L 4-8 | 40-33 | 2 | 11,355 | Javier Vazquez | Cory Lidle | Cory Lidle | Javier Vazquez | | 319 | 318 | 1 |
| 2003-06-21 | vs TOR | 74 | W 8-5 | 41-33 | 2 | 11,483 | Sun-Woo Kim | Mark Hendrickson | Luis Ayala | Cliff Politte | Rocky Biddle | 327 | 323 | 4 |
| 2003-06-22 | vs TOR | 75 | L 2-4 | 41-34 | 2 | 15,508 | Livan Hernandez | Roy Halladay | Roy Halladay | Livan Hernandez | Cliff Politte | 329 | 327 | 2 |
| 2003-06-23 | vs PIT | 76 | W 3-0 | 42-34 | 2 | 5,641 | Claudio Vargas | Jeff Suppan | Claudio Vargas | Jeff Suppan | Rocky Biddle | 332 | 327 | 5 |
| 2003-06-24 | vs PIT | 77 | W 6-4 | 43-34 | 2 | 5,872 | Tomo Ohka | Jeff D'Amico | Tomo Ohka | Jeff D'Amico | Rocky Biddle | 338 | 331 | 7 |
| 2003-06-25 | vs PIT | 78 | L 5-6 | 43-35 | 2 | 5,717 | Javier Vazquez | Kip Wells | Scott Sauerbeck | Joey Eischen | Mike Williams | 343 | 337 | 6 |
| 2003-06-27 | @ TOR | 79 | L 5-6 | 43-36 | 3 | 24,024 | Livan Hernandez | Roy Halladay | Trever Miller | Julio Manon | | 348 | 343 | 5 |
| 2003-06-28 | @ TOR | 80 | W 4-2 | 44-36 | 3 | 33,334 | Claudio Vargas | Doug Davis | Claudio Vargas | Doug Davis | Rocky Biddle | 352 | 345 | 7 |
| 2003-06-29 | @ TOR | 81 | W 10-2 | 45-36 | 3 | 37,354 | Tomo Ohka | Kelvim Escobar | Tomo Ohka | Kelvim Escobar | | 362 | 347 | 15 |
| 2003-06-30 | @ NYN | 82 | L 1-3 | 45-37 | 3 | 29,829 | Javier Vazquez | Steve Trachsel | Steve Trachsel | Javier Vazquez | Armando Benitez | 363 | 350 | 13 |
| 2003-07-01 | @ NYN | 83 | L 6-7 | 45-38 | 3 | 30,084 | Sun-Woo Kim | Aaron Heilman | Armando Benitez | Julio Manon | | 369 | 357 | 12 |
| 2003-07-02 | @ NYN | 84 | W 11-4 | 46-38 | 3 | 35,547 | Livan Hernandez | Jae Weong Seo | Livan Hernandez | Jae Weong Seo | | 380 | 361 | 19 |
| 2003-07-03 | @ ATL | 85 | W 5-4 | 47-38 | 3 | 31,607 | Claudio Vargas | Shane Reynolds | Claudio Vargas | Shane Reynolds | Julio Manon | 385 | 365 | 20 |
| 2003-07-04 | @ ATL | 86 | L 6-8 | 47-39 | 3 | 48,923 | Tomo Ohka | Russ Ortiz | Russ Ortiz | Tomo Ohka | John Smoltz | 391 | 373 | 18 |
| 2003-07-05 | @ ATL | 87 | L 2-3 | 47-40 | 3 | 34,454 | Javier Vazquez | Greg Maddux | Jung Bong | Rocky Biddle | | 393 | 376 | 17 |
| 2003-07-06 | @ ATL | 88 | L 5-7 | 47-41 | 3 | 27,724 | Tim Drew | Mike Hampton | Mike Hampton | Tim Drew | John Smoltz | 398 | 383 | 15 |
| 2003-07-07 | vs PHI | 89 | W 8-1 | 48-41 | 3 | 7,099 | Livan Hernandez | Brandon Duckworth | Livan Hernandez | Brandon Duckworth | | 406 | 384 | 22 |
| 2003-07-08 | vs PHI | 90 | L 6-13 | 48-42 | 3 | 8,225 | Claudio Vargas | Brett Myers | Brett Myers | Claudio Vargas | | 412 | 397 | 15 |
| 2003-07-09 | vs PHI | 91 | L 0-2 | 48-43 | 3 | 7,005 | Tomo Ohka | Kevin Millwood | Kevin Millwood | Tomo Ohka | | 412 | 399 | 13 |
| 2003-07-11 | vs FLO | 92 | L 4-5 | 48-44 | 3 | 7,251 | Javier Vazquez | Brad Penny | Brad Penny | Rocky Biddle | Braden Looper | 416 | 404 | 12 |
| 2003-07-12 | vs FLO | 93 | W 7-1 | 49-44 | 3 | 28,170 | Livan Hernandez | Mark Redman | Livan Hernandez | Mark Redman | | 423 | 405 | 18 |
| 2003-07-13 | vs FLO | 94 | L 4-11 | 49-45 | 3 | 16,084 | Claudio Vargas | Dontrelle Willis | Dontrelle Willis | Claudio Vargas | | 427 | 416 | 11 |
| 2003-07-17 | @ PHI | 95 | L 2-5 | 49-46 | 4 | 23,874 | Tomo Ohka | Kevin Millwood | Dan Plesac | Tim Drew | | 429 | 421 | 8 |
| 2003-07-18 | @ PHI | 96 | W 3-1 | 50-46 | 4 | 22,789 | Javier Vazquez | Randy Wolf | Javier Vazquez | Randy Wolf | | 432 | 422 | 10 |
| 2003-07-19 | @ PHI | 97 | L 3-4 | 50-47 | 4 | 28,794 | Livan Hernandez | Vicente Padilla | Jose Mesa | Hector Almonte | | 435 | 426 | 9 |
| 2003-07-20 | @ PHI | 98 | L 2-3 | 50-48 | 4 | 37,552 | Claudio Vargas | Brett Myers | Brett Myers | Claudio Vargas | Jose Mesa | 437 | 429 | 8 |
| 2003-07-21 | @ FLO | 99 | L 1-4 | 50-49 | 4 | 10,769 | Eric Knott | Josh Beckett | Josh Beckett | Eric Knott | | 438 | 433 | 5 |
| 2003-07-22 | @ FLO | 100 | L 1-9 | 50-50 | 4 | 10,512 | Tomo Ohka | Carl Pavano | Carl Pavano | Tomo Ohka | | 439 | 442 | -3 |
| 2003-07-23 | vs NYN | 101 | W 5-2 | 51-50 | 4 | 8,853 | Javier Vazquez | Jae Weong Seo | Javier Vazquez | Jae Weong Seo | Rocky Biddle | 444 | 444 | 0 |
| 2003-07-24 | vs NYN | 102 | W 5-1 | 52-50 | 4 | 9,337 | Livan Hernandez | Tom Glavine | Livan Hernandez | Tom Glavine | Rocky Biddle | 449 | 445 | 4 |
| 2003-07-25 | vs ATL | 103 | W 9-8 | 53-50 | 4 | 10,069 | Claudio Vargas | Horacio Ramirez | Luis Ayala | Jung Bong | | 458 | 453 | 5 |
| 2003-07-26 | vs ATL | 104 | L 4-15 | 53-51 | 4 | 14,132 | Zach Day | Shane Reynolds | Shane Reynolds | Zach Day | | 462 | 468 | -6 |
| 2003-07-27 | vs ATL | 105 | W 13-10 | 54-51 | 4 | 16,074 | Tomo Ohka | Greg Maddux | Julio Manon | Ray King | Rocky Biddle | 475 | 478 | -3 |
| 2003-07-28 | vs ATL | 106 | L 8-10 | 54-52 | 4 | 9,750 | Javier Vazquez | Mike Hampton | Mike Hampton | Javier Vazquez | John Smoltz | 483 | 488 | -5 |
| 2003-07-29 | vs SLN | 107 | L 1-2 | 54-53 | 4 | 7,418 | Livan Hernandez | Garrett Stephenson | Garrett Stephenson | Livan Hernandez | | 484 | 490 | -6 |
| 2003-07-30 | vs SLN | 108 | L 1-11 | 54-54 | 4 | 6,129 | Claudio Vargas | Dan Haren | Dan Haren | Claudio Vargas | | 485 | 501 | -16 |
| 2003-07-31 | vs SLN | 109 | W 3-2 | 55-54 | 4 | 9,145 | Zach Day | Woody Williams | Zach Day | Woody Williams | Rocky Biddle | 488 | 503 | -15 |
| 2003-08-01 | vs MIL | 110 | W 8-4 | 56-54 | 4 | 6,518 | Tomo Ohka | Wayne Franklin | Tomo Ohka | Wayne Franklin | | 496 | 507 | -11 |
| 2003-08-02 | vs MIL | 111 | W 7-1 | 57-54 | 4 | 22,180 | Javier Vazquez | David Manning | Javier Vazquez | David Manning | | 503 | 508 | -5 |
| 2003-08-03 | vs MIL | 112 | W 4-2 | 58-54 | 4 | 17,953 | Livan Hernandez | Ben Sheets | Livan Hernandez | Ben Sheets | Rocky Biddle | 507 | 510 | -3 |
| 2003-08-05 | @ ARI | 113 | L 5-8 | 58-55 | 4 | 37,959 | Claudio Vargas | Randy Johnson | Randy Johnson | Claudio Vargas | Matt Mantei | 512 | 518 | -6 |
| 2003-08-06 | @ ARI | 114 | L 2-3 | 58-56 | 4 | 28,328 | Zach Day | Curt Schilling | Eddie Oropesa | Luis Ayala | Matt Mantei | 514 | 521 | -7 |
| 2003-08-07 | @ ARI | 115 | L 4-5 | 58-57 | 4 | 28,852 | Tomo Ohka | Miguel Batista | Jose Valverde | Eric Knott | | 518 | 526 | -8 |
| 2003-08-08 | @ HOU | 116 | L 1-5 | 58-58 | 4 | 30,037 | Javier Vazquez | Jeriome Robertson | Jeriome Robertson | Javier Vazquez | | 519 | 531 | -12 |
| 2003-08-09 | @ HOU | 117 | W 3-1 | 59-58 | 4 | 35,295 | Livan Hernandez | Jared Fernandez | Livan Hernandez | Jared Fernandez | | 522 | 532 | -10 |
| 2003-08-10 | @ HOU | 118 | L 2-8 | 59-59 | 4 | 32,340 | Scott Downs | Ron Villone | Ron Villone | Scott Downs | | 524 | 540 | -16 |
| 2003-08-11 | vs COL | 119 | W 3-1 | 60-59 | 4 | 6,401 | Zach Day | Jason Jennings | Zach Day | Jason Jennings | Rocky Biddle | 527 | 541 | -14 |
| 2003-08-12 | vs COL | 120 | L 3-6 | 60-60 | 4 | 7,277 | Tomo Ohka | Chin-hui Tsao | Brian Fuentes | Rocky Biddle | Javier Lopez | 530 | 547 | -17 |
| 2003-08-13 | vs COL | 121 | W 6-5 | 61-60 | 4 | 6,724 | Javier Vazquez | Denny Stark | Javier Vazquez | Denny Stark | Luis Ayala | 536 | 552 | -16 |
| 2003-08-15 | vs SFN | 122 | W 4-1 | 62-60 | 4 | 10,551 | Livan Hernandez | Jesse Foppert | Livan Hernandez | Jesse Foppert | | 540 | 553 | -13 |
| 2003-08-16 | vs SFN | 123 | W 4-1 | 63-60 | 4 | 16,446 | Zach Day | Jason Schmidt | Zach Day | Jason Schmidt | Rocky Biddle | 544 | 554 | -10 |
| 2003-08-17 | vs SFN | 124 | W 4-2 | 64-60 | 4 | 17,665 | Tomo Ohka | Sidney Ponson | Rocky Biddle | Sidney Ponson | | 548 | 556 | -8 |
| 2003-08-18 | vs SFN | 125 | W 4-0 | 65-60 | 4 | 9,224 | Javier Vazquez | Dustin Hermanson | Javier Vazquez | Dustin Hermanson | | 552 | 556 | -4 |
| 2003-08-19 | @ LAN | 126 | W 7-5 | 66-60 | 4 | 30,107 | T.J. Tucker | Kevin Brown | Luis Ayala | Paul Quantrill | Rocky Biddle | 559 | 561 | -2 |
| 2003-08-20 | @ LAN | 127 | L 1-4 | 66-61 | 4 | 31,427 | Livan Hernandez | Wilson Alvarez | Eric Gagne | Rocky Biddle | | 560 | 565 | -5 |
| 2003-08-21 | @ LAN | 128 | L 1-2 | 66-62 | 4 | 33,319 | Zach Day | Odalis Perez | Odalis Perez | Zach Day | Eric Gagne | 561 | 567 | -6 |
| 2003-08-22 | @ SDN | 129 | L 3-5 | 66-63 | 4 | 17,590 | Tomo Ohka | Brian Lawrence | Scott Linebrink | Joey Eischen | Rod Beck | 564 | 572 | -8 |
| 2003-08-23 | @ SDN | 130 | L 0-1 | 66-64 | 4 | 29,450 | Javier Vazquez | Adam Eaton | Mike Matthews | Rocky Biddle | | 564 | 573 | -9 |
| 2003-08-24 | @ SDN | 131 | W 8-4 | 67-64 | 4 | 24,707 | T.J. Tucker | Kevin Jarvis | Eric Knott | Kevin Jarvis | | 572 | 577 | -5 |
| 2003-08-25 | vs PHI | 132 | W 12-1 | 68-64 | 4 | 30,501 | Livan Hernandez | Randy Wolf | Livan Hernandez | Randy Wolf | | 584 | 578 | 6 |
| 2003-08-26 | vs PHI | 133 | W 14-10 | 69-64 | 4 | 12,509 | Zach Day | Vicente Padilla | Joey Eischen | Mike Williams | Luis Ayala | 598 | 588 | 10 |
| 2003-08-27 | vs PHI | 134 | W 9-6 | 70-64 | 4 | 20,105 | Tomo Ohka | Brett Myers | Hector Almonte | Dan Plesac | Rocky Biddle | 607 | 594 | 13 |
| 2003-08-28 | vs PHI | 135 | W 4-0 | 71-64 | 4 | 20,030 | Javier Vazquez | Amaury Telemaco | Javier Vazquez | Amaury Telemaco | | 611 | 594 | 17 |
| 2003-08-29 | @ FLO | 136 | L 2-3 | 71-65 | 4 | 12,231 | T.J. Tucker | Josh Beckett | Braden Looper | Rocky Biddle | | 613 | 597 | 16 |
| 2003-08-30 | @ FLO | 137 | L 3-4 | 71-66 | 4 | 20,724 | Livan Hernandez | Carl Pavano | Carl Pavano | Livan Hernandez | Braden Looper | 616 | 601 | 15 |
| 2003-08-31 | @ FLO | 138 | L 3-5 | 71-67 | 4 | 11,105 | Zach Day | Mark Redman | Mark Redman | Zach Day | Ugueth Urbina | 619 | 606 | 13 |
| 2003-09-01 | @ FLO | 139 | L 2-5 | 71-68 | 4 | 12,413 | Tomo Ohka | Brad Penny | Brad Penny | Tomo Ohka | Braden Looper | 621 | 611 | 10 |
| 2003-09-02 | @ PHI | 140 | L 3-5 | 71-69 | 4 | 26,719 | Javier Vazquez | Amaury Telemaco | Rheal Cormier | Javier Vazquez | Dan Plesac | 624 | 616 | 8 |
| 2003-09-03 | @ PHI | 141 | L 3-8 | 71-70 | 4 | 18,002 | T.J. Tucker | Kevin Millwood | Kevin Millwood | T.J. Tucker | | 627 | 624 | 3 |
| 2003-09-05 | vs FLO | 142 | W 6-2 | 72-70 | 4 | 11,509 | Livan Hernandez | Mark Redman | Livan Hernandez | Mark Redman | | 633 | 626 | 7 |
| 2003-09-06 | vs FLO | 143 | L 4-14 | 72-71 | 4 | 14,570 | Tomo Ohka | Brad Penny | Brad Penny | Tomo Ohka | | 637 | 640 | -3 |
| 2003-09-07 | vs FLO | 144 | L 1-3 | 72-72 | 4 | 12,647 | Javier Vazquez | Dontrelle Willis | Dontrelle Willis | Javier Vazquez | Braden Looper | 638 | 643 | -5 |
| 2003-09-09 | vs CHN | 145 | L 3-4 | 72-73 | 4 | 15,632 | Zach Day | Carlos Zambrano | Carlos Zambrano | Zach Day | Joe Borowski | 641 | 647 | -6 |
| 2003-09-10 | vs CHN | 146 | W 8-4 | 73-73 | 4 | 18,002 | Livan Hernandez | Matt Clement | Luis Ayala | Kyle Farnsworth | | 649 | 651 | -2 |
| 2003-09-11 | vs CHN | 147 | W 3-2 | 74-73 | 4 | 12,559 | Tomo Ohka | Mark Prior | Tomo Ohka | Mark Prior | Joey Eischen | 652 | 653 | -1 |
| 2003-09-12 | vs NYN | 148 | W 7-4 | 75-73 | 4 | 10,701 | T.J. Tucker | Al Leiter | T.J. Tucker | Al Leiter | Luis Ayala | 659 | 657 | 2 |
| 2003-09-13 | vs NYN | 149 | L 4-5 | 75-74 | 4 | 15,086 | Javier Vazquez | Steve Trachsel | Steve Trachsel | Javier Vazquez | Grant Roberts | 663 | 662 | 1 |
| 2003-09-14 | vs NYN | 150 | W 7-3 | 76-74 | 4 | 21,417 | Zach Day | Tom Glavine | Zach Day | Tom Glavine | | 670 | 665 | 5 |
| 2003-09-15 | vs ATL | 151 | L 6-10 | 76-75 | 4 | 9,696 | Livan Hernandez | Horacio Ramirez | Horacio Ramirez | Livan Hernandez | | 676 | 675 | 1 |
| 2003-09-16 | vs ATL | 152 | W 5-4 | 77-75 | 4 | 9,843 | Tomo Ohka | Greg Maddux | Rocky Biddle | Roberto Hernandez | | 681 | 679 | 2 |
| 2003-09-17 | vs ATL | 153 | L 4-14 | 77-76 | 4 | 17,526 | T.J. Tucker | Mike Hampton | Mike Hampton | T.J. Tucker | | 685 | 693 | -8 |
| 2003-09-18 | @ NYN | 154 | W 1-0 | 78-76 | 4 | 18,914 | Javier Vazquez | Steve Trachsel | Javier Vazquez | Steve Trachsel | Chad Cordero | 686 | 693 | -7 |
| 2003-09-19 | @ NYN | 155 | W 7-1 | 79-76 | 4 | 33,083 | Zach Day | Tom Glavine | Zach Day | Tom Glavine | | 693 | 694 | -1 |
| 2003-09-20 | @ NYN | 156 | W 4-3 | 80-76 | 4 | 37,294 | Livan Hernandez | Aaron Heilman | Chad Cordero | Mike Stanton | Rocky Biddle | 697 | 697 | 0 |
| 2003-09-21 | @ NYN | 157 | W 4-2 | 81-76 | 4 | 28,702 | Tomo Ohka | Jae Weong Seo | Luis Ayala | Grant Roberts | Rocky Biddle | 701 | 699 | 2 |
| 2003-09-23 | @ ATL | 158 | L 0-2 | 81-77 | 4 | 22,539 | Javier Vazquez | Shane Reynolds | Jaret Wright | Javier Vazquez | John Smoltz | 701 | 701 | 0 |
| 2003-09-24 | @ ATL | 159 | L 1-9 | 81-78 | 4 | 23,594 | Zach Day | Russ Ortiz | Russ Ortiz | Zach Day | | 702 | 710 | -8 |
| 2003-09-26 | @ CIN | 160 | W 5-1 | 82-78 | 4 | 28,870 | Tomo Ohka | Aaron Harang | Tomo Ohka | Aaron Harang | | 707 | 711 | -4 |
| 2003-09-27 | @ CIN | 161 | L 2-4 | 82-79 | 4 | 31,199 | Livan Hernandez | Brian Reith | Brian Reith | Livan Hernandez | | 709 | 715 | -6 |
| 2003-09-28 | @ CIN | 162 | W 2-1 | 83-79 | 4 | 32,322 | Claudio Vargas | Scott Randall | T.J. Tucker | Scott Randall | Rocky Biddle | 711 | 716 | -5 |