| 2004-04-05 | vs CHA | 1 | W 9-7 | 1-0 | 2 | 41,575 | Brian Anderson | Mark Buehrle | D.J. Carrasco | Damaso Marte | | 9 | 7 | 2 |
| 2004-04-07 | vs CHA | 2 | L 3-4 | 1-1 | 4 | 16,134 | Darrell May | Esteban Loaiza | Esteban Loaiza | Darrell May | Billy Koch | 12 | 11 | 1 |
| 2004-04-08 | vs CLE | 3 | L 1-6 | 1-2 | 5 | 14,671 | Jeremy Affeldt | Jeff D'Amico | Jeff D'Amico | Jeremy Affeldt | | 13 | 17 | -4 |
| 2004-04-09 | vs CLE | 4 | W 3-1 | 2-2 | 3 | 28,535 | Jimmy Gobble | Jason Stanford | Jason Grimsley | Jack Cressend | Curt Leskanic | 16 | 18 | -2 |
| 2004-04-10 | vs CLE | 5 | W 7-6 | 3-2 | 3 | 21,889 | Brian Anderson | CC Sabathia | Scott Sullivan | Rafael Betancourt | | 23 | 24 | -1 |
| 2004-04-11 | vs CLE | 6 | W 5-3 | 4-2 | 2 | 16,933 | Dennys Reyes | Jason Davis | Scott Sullivan | Jose Jimenez | Curt Leskanic | 28 | 27 | 1 |
| 2004-04-13 | @ CHA | 7 | L 5-12 | 4-3 | 3 | 37,706 | Darrell May | Esteban Loaiza | Esteban Loaiza | Darrell May | | 33 | 39 | -6 |
| 2004-04-14 | @ CHA | 8 | L 9-10 | 4-4 | 3 | 11,765 | Jeremy Affeldt | Jon Garland | Jon Adkins | Curt Leskanic | | 42 | 49 | -7 |
| 2004-04-15 | @ CHA | 9 | L 5-6 | 4-5 | 4 | 15,150 | Brian Anderson | Mark Buehrle | Damaso Marte | D.J. Carrasco | | 47 | 55 | -8 |
| 2004-04-16 | @ MIN | 10 | L 7-9 | 4-6 | 4 | 22,553 | Jimmy Gobble | Johan Santana | Juan Rincon | Jaime Cerda | Joe Nathan | 54 | 64 | -10 |
| 2004-04-17 | @ MIN | 11 | L 4-8 | 4-7 | 4 | 25,420 | Kevin Appier | Kyle Lohse | Kyle Lohse | Kevin Appier | J.C. Romero | 58 | 72 | -14 |
| 2004-04-18 | @ MIN | 12 | L 3-8 | 4-8 | 5 | 21,079 | Darrell May | Seth Greisinger | Joe Roa | Darrell May | | 61 | 80 | -19 |
| 2004-04-20 | @ CLE | 13 | W 15-5 | 5-8 | 4 | 13,563 | Brian Anderson | Chad Durbin | Brian Anderson | Chad Durbin | | 76 | 85 | -9 |
| 2004-04-22 | @ CLE | 14 | L 4-5 | 5-9 | 5 | 15,720 | Jeremy Affeldt | Jeff D'Amico | Rafael Betancourt | Jason Grimsley | David Riske | 80 | 90 | -10 |
| 2004-04-23 | vs MIN | 15 | L 5-7 | 5-10 | 5 | 20,103 | Kevin Appier | Kyle Lohse | J.C. Romero | Curt Leskanic | Joe Nathan | 85 | 97 | -12 |
| 2004-04-24 | vs MIN | 16 | W 10-1 | 6-10 | 4 | 25,525 | Darrell May | Seth Greisinger | Shawn Camp | Seth Greisinger | | 95 | 98 | -3 |
| 2004-04-25 | vs MIN | 17 | L 2-4 | 6-11 | 5 | 23,159 | Brian Anderson | Carlos Silva | Carlos Silva | Brian Anderson | Joe Nathan | 97 | 102 | -5 |
| 2004-04-27 | vs TEX | 18 | L 2-3 | 6-12 | 5 | 15,529 | Jeremy Affeldt | R.A. Dickey | R.A. Dickey | Jeremy Affeldt | Francisco Cordero | 99 | 105 | -6 |
| 2004-04-28 | vs TEX | 19 | W 5-3 | 7-12 | 5 | 15,530 | Jimmy Gobble | Kenny Rogers | Jimmy Gobble | Kenny Rogers | Mike MacDougal | 104 | 108 | -4 |
| 2004-04-29 | vs TEX | 20 | L 7-9 | 7-13 | 5 | 13,663 | Dennys Reyes | Chan Ho Park | Carlos Almanzar | Curt Leskanic | Francisco Cordero | 111 | 117 | -6 |
| 2004-04-30 | @ NYA | 21 | L 2-5 | 7-14 | 5 | 43,237 | Brian Anderson | Javier Vazquez | Javier Vazquez | Brian Anderson | Mariano Rivera | 113 | 122 | -9 |
| 2004-05-01 | @ NYA | 22 | L 4-12 | 7-15 | 5 | 54,103 | Eduardo Villacis | Jon Lieber | Jon Lieber | Eduardo Villacis | | 117 | 134 | -17 |
| 2004-05-02 | @ NYA | 23 | L 2-4 | 7-16 | 5 | 49,208 | Jeremy Affeldt | Mike Mussina | Mike Mussina | Jeremy Affeldt | Mariano Rivera | 119 | 138 | -19 |
| 2004-05-03 | @ TOR | 24 | W 3-2 | 8-16 | 5 | 13,007 | Jimmy Gobble | Justin Miller | Nate Field | Terry Adams | Jaime Cerda | 122 | 140 | -18 |
| 2004-05-04 | @ TOR | 25 | L 4-5 | 8-17 | 5 | 20,011 | Darrell May | Pat Hentgen | Pat Hentgen | Darrell May | Jason Frasor | 126 | 145 | -19 |
| 2004-05-05 | @ TOR | 26 | L 3-10 | 8-18 | 5 | 14,103 | Brian Anderson | Roy Halladay | Roy Halladay | Brian Anderson | | 129 | 155 | -26 |
| 2004-05-07 | @ BOS | 27 | L 6-7 | 8-19 | 5 | 35,280 | Jeremy Affeldt | Tim Wakefield | Mike Timlin | Mike MacDougal | | 135 | 162 | -27 |
| 2004-05-08 | @ BOS | 28 | L 1-9 | 8-20 | 5 | 34,929 | Jimmy Gobble | Curt Schilling | Curt Schilling | Jimmy Gobble | | 136 | 171 | -35 |
| 2004-05-09 | @ BOS | 29 | W 8-4 | 9-20 | 5 | 34,589 | Darrell May | Derek Lowe | Darrell May | Derek Lowe | | 144 | 175 | -31 |
| 2004-05-10 | vs TOR | 30 | L 3-9 | 9-21 | 5 | 13,803 | Brian Anderson | Pat Hentgen | Pat Hentgen | Brian Anderson | | 147 | 184 | -37 |
| 2004-05-11 | vs TOR | 31 | W 5-1 | 10-21 | 5 | 15,779 | Dennys Reyes | Roy Halladay | Shawn Camp | Roy Halladay | | 152 | 185 | -33 |
| 2004-05-12 | vs TOR | 32 | W 4-3 | 11-21 | 5 | 29,309 | Jeremy Affeldt | Ted Lilly | Nate Field | Terry Adams | | 156 | 188 | -32 |
| 2004-05-14 | vs OAK | 33 | L 2-6 | 11-22 | 5 | 35,772 | Jimmy Gobble | Tim Hudson | Tim Hudson | Jimmy Gobble | | 158 | 194 | -36 |
| 2004-05-15 | vs OAK | 34 | L 1-3 | 11-23 | 5 | 30,838 | Darrell May | Mark Mulder | Mark Mulder | Darrell May | | 159 | 197 | -38 |
| 2004-05-16 | vs OAK | 35 | L 2-6 | 11-24 | 5 | 25,054 | Brian Anderson | Barry Zito | Barry Zito | Brian Anderson | | 161 | 203 | -42 |
| 2004-05-18 | @ TEX | 36 | W 7-6 | 12-24 | 5 | 26,247 | Jeremy Affeldt | R.A. Dickey | Scott Sullivan | R.A. Dickey | Nate Field | 168 | 209 | -41 |
| 2004-05-19 | @ TEX | 37 | W 5-3 | 13-24 | 5 | 32,374 | Jimmy Gobble | Chan Ho Park | Jimmy Gobble | Chan Ho Park | Justin Huisman | 173 | 212 | -39 |
| 2004-05-20 | @ TEX | 38 | L 3-6 | 13-25 | 5 | 25,149 | Darrell May | Kenny Rogers | Kenny Rogers | Darrell May | Francisco Cordero | 176 | 218 | -42 |
| 2004-05-21 | @ OAK | 39 | L 0-7 | 13-26 | 5 | 27,080 | Brian Anderson | Mark Mulder | Mark Mulder | Brian Anderson | | 176 | 225 | -49 |
| 2004-05-22 | @ OAK | 40 | L 4-5 | 13-27 | 5 | 26,081 | Zack Greinke | Barry Zito | Justin Duchscherer | Scott Sullivan | | 180 | 230 | -50 |
| 2004-05-23 | @ OAK | 41 | L 2-3 | 13-28 | 5 | 33,476 | Dennys Reyes | Rich Harden | Arthur Rhodes | Nate Field | | 182 | 233 | -51 |
| 2004-05-25 | vs DET | 42 | W 4-3 | 14-28 | 5 | 14,297 | Jimmy Gobble | Mike Maroth | Jason Grimsley | Mike Maroth | Jeremy Affeldt | 186 | 236 | -50 |
| 2004-05-26 | vs DET | 43 | W 7-3 | 15-28 | 5 | 19,534 | Darrell May | Gary Knotts | Darrell May | Gary Knotts | Jeremy Affeldt | 193 | 239 | -46 |
| 2004-05-27 | vs DET | 44 | L 7-17 | 15-29 | 5 | 15,475 | Brian Anderson | Nate Robertson | Nate Robertson | Brian Anderson | | 200 | 256 | -56 |
| 2004-05-28 | vs MIN | 45 | W 2-1 | 16-29 | 5 | 30,614 | Zack Greinke | Brad Radke | Jeremy Affeldt | Juan Rincon | | 202 | 257 | -55 |
| 2004-05-29 | vs MIN | 46 | W 5-2 | 17-29 | 5 | 24,676 | Dennys Reyes | Johan Santana | Dennys Reyes | Johan Santana | Jeremy Affeldt | 207 | 259 | -52 |
| 2004-05-30 | vs MIN | 47 | L 3-8 | 17-30 | 5 | 22,305 | Jimmy Gobble | Kyle Lohse | Kyle Lohse | Jimmy Gobble | | 210 | 267 | -57 |
| 2004-05-31 | @ DET | 48 | L 4-8 | 17-31 | 5 | 12,982 | Darrell May | Gary Knotts | Gary Knotts | Darrell May | | 214 | 275 | -61 |
| 2004-06-01 | @ DET | 49 | W 5-3 | 18-31 | 5 | 12,685 | Chris George | Nate Robertson | Jason Grimsley | Esteban Yan | Jeremy Affeldt | 219 | 278 | -59 |
| 2004-06-02 | @ DET | 50 | L 0-2 | 18-32 | 5 | 12,186 | Zack Greinke | Jason Johnson | Jason Johnson | Zack Greinke | Ugueth Urbina | 219 | 280 | -61 |
| 2004-06-03 | @ DET | 51 | W 9-6 | 19-32 | 5 | 16,711 | Dennys Reyes | Jeremy Bonderman | Dennys Reyes | Jeremy Bonderman | Jeremy Affeldt | 228 | 286 | -58 |
| 2004-06-04 | vs BOS | 52 | W 5-2 | 20-32 | 5 | 28,182 | Jimmy Gobble | Tim Wakefield | Jimmy Gobble | Tim Wakefield | Jeremy Affeldt | 233 | 288 | -55 |
| 2004-06-05 | vs BOS | 53 | L 4-8 | 20-33 | 5 | 29,968 | Darrell May | Curt Schilling | Curt Schilling | Darrell May | | 237 | 296 | -59 |
| 2004-06-06 | vs BOS | 54 | L 3-5 | 20-34 | 5 | 22,964 | Chris George | Derek Lowe | Derek Lowe | Jason Grimsley | Keith Foulke | 240 | 301 | -61 |
| 2004-06-08 | vs MON | 55 | W 4-2 | 21-34 | 5 | 15,209 | Zack Greinke | Tony Armas | Zack Greinke | Tony Armas | Jeremy Affeldt | 244 | 303 | -59 |
| 2004-06-10 | vs MON | 56 | L 0-8 | 21-36 | 5 | 0 | Dennys Reyes | Zach Day | Zach Day | Dennys Reyes | | 244 | 311 | -67 |
| 2004-06-10 | vs MON | 57 | L 2-7 | 21-36 | 5 | 16,891 | Jimmy Gobble | Tomo Ohka | Sun-Woo Kim | Jimmy Gobble | | 246 | 318 | -72 |
| 2004-06-11 | vs NYN | 58 | W 7-5 | 22-36 | 5 | 23,243 | Darrell May | Jae Weong Seo | Darrell May | Jae Weong Seo | Jeremy Affeldt | 253 | 323 | -70 |
| 2004-06-12 | vs NYN | 59 | W 4-3 | 23-36 | 5 | 23,890 | Chris George | Al Leiter | Jeremy Affeldt | David Weathers | | 257 | 326 | -69 |
| 2004-06-13 | vs NYN | 60 | L 2-5 | 23-37 | 5 | 24,632 | Zack Greinke | Tom Glavine | Tom Glavine | Zack Greinke | Braden Looper | 259 | 331 | -72 |
| 2004-06-15 | @ ATL | 61 | L 2-3 | 23-38 | 5 | 23,350 | Dennys Reyes | Russ Ortiz | Chris Reitsma | Jason Grimsley | John Smoltz | 261 | 334 | -73 |
| 2004-06-16 | @ ATL | 62 | W 10-4 | 24-38 | 5 | 27,048 | Jimmy Gobble | Jaret Wright | Jaime Cerda | Chris Reitsma | | 271 | 338 | -67 |
| 2004-06-17 | @ ATL | 63 | W 10-4 | 25-38 | 5 | 28,578 | Darrell May | John Thomson | Darrell May | John Thomson | | 281 | 342 | -61 |
| 2004-06-18 | @ PHI | 64 | W 10-4 | 26-38 | 5 | 43,571 | Chris George | Paul Abbott | Chris George | Paul Abbott | | 291 | 346 | -55 |
| 2004-06-19 | @ PHI | 65 | L 2-4 | 26-39 | 5 | 44,234 | Zack Greinke | Eric Milton | Eric Milton | Zack Greinke | Billy Wagner | 293 | 350 | -57 |
| 2004-06-20 | @ PHI | 66 | L 2-8 | 26-40 | 5 | 44,411 | Dennys Reyes | Brian Powell | Brian Powell | Dennys Reyes | | 295 | 358 | -63 |
| 2004-06-22 | vs DET | 67 | W 8-1 | 27-40 | 5 | 16,276 | Jimmy Gobble | Mike Maroth | Jimmy Gobble | Mike Maroth | Nate Field | 303 | 359 | -56 |
| 2004-06-23 | vs DET | 68 | W 7-3 | 28-40 | 5 | 18,493 | Darrell May | Gary Knotts | Darrell May | Gary Knotts | | 310 | 362 | -52 |
| 2004-06-24 | vs DET | 69 | L 3-12 | 28-41 | 5 | 18,172 | Chris George | Nate Robertson | Nate Robertson | Chris George | | 313 | 374 | -61 |
| 2004-06-25 | vs SLN | 70 | L 2-5 | 28-42 | 5 | 40,628 | Zack Greinke | Matt Morris | Matt Morris | Zack Greinke | Jason Isringhausen | 315 | 379 | -64 |
| 2004-06-26 | vs SLN | 71 | L 1-3 | 28-43 | 5 | 40,963 | Dennys Reyes | Woody Williams | Julian Tavarez | Rudy Seanez | Jason Isringhausen | 316 | 382 | -66 |
| 2004-06-27 | vs SLN | 72 | L 3-10 | 28-44 | 5 | 36,651 | Jimmy Gobble | Jason Marquis | Jason Marquis | Jimmy Gobble | | 319 | 392 | -73 |
| 2004-06-28 | vs BAL | 73 | L 1-10 | 28-45 | 5 | 14,521 | Darrell May | Erik Bedard | Erik Bedard | Darrell May | | 320 | 402 | -82 |
| 2004-06-29 | vs BAL | 74 | W 4-3 | 29-45 | 5 | 15,575 | Mike Wood | Sidney Ponson | Mike Wood | Sidney Ponson | Shawn Camp | 324 | 405 | -81 |
| 2004-06-30 | vs BAL | 75 | L 4-13 | 29-46 | 5 | 14,970 | Brian Anderson | Daniel Cabrera | Daniel Cabrera | Brian Anderson | | 328 | 418 | -90 |
| 2004-07-01 | vs BAL | 76 | L 2-3 | 29-47 | 5 | 22,960 | Zack Greinke | Rodrigo Lopez | Rodrigo Lopez | Zack Greinke | Jorge Julio | 330 | 421 | -91 |
| 2004-07-02 | @ SDN | 77 | L 5-7 | 29-48 | 5 | 38,965 | Dennys Reyes | Jake Peavy | Jake Peavy | Dennys Reyes | Trevor Hoffman | 335 | 428 | -93 |
| 2004-07-03 | @ SDN | 78 | L 4-5 | 29-49 | 5 | 43,152 | Darrell May | Adam Eaton | Scott Linebrink | Scott Sullivan | Trevor Hoffman | 339 | 433 | -94 |
| 2004-07-04 | @ SDN | 79 | L 1-7 | 29-50 | 5 | 31,490 | Mike Wood | David Wells | David Wells | Mike Wood | | 340 | 440 | -100 |
| 2004-07-05 | @ MIN | 80 | L 0-9 | 29-51 | 5 | 16,191 | Jimmy Gobble | Brad Radke | Brad Radke | Jimmy Gobble | | 340 | 449 | -109 |
| 2004-07-06 | @ MIN | 81 | L 0-4 | 29-52 | 5 | 18,038 | Zack Greinke | Johan Santana | Johan Santana | Zack Greinke | | 340 | 453 | -113 |
| 2004-07-07 | @ MIN | 82 | L 0-12 | 29-53 | 5 | 19,534 | Dennys Reyes | Kyle Lohse | Kyle Lohse | Dennys Reyes | | 340 | 465 | -125 |
| 2004-07-09 | @ BAL | 83 | W 7-0 | 30-53 | 5 | 43,947 | Darrell May | Erik Bedard | Darrell May | Erik Bedard | | 347 | 465 | -118 |
| 2004-07-10 | @ BAL | 84 | L 2-7 | 30-54 | 5 | 33,493 | Mike Wood | Daniel Cabrera | Daniel Cabrera | Mike Wood | | 349 | 472 | -123 |
| 2004-07-11 | @ BAL | 85 | W 11-7 | 31-54 | 5 | 31,042 | Jimmy Gobble | Rodrigo Lopez | Jimmy Gobble | Rodrigo Lopez | | 360 | 479 | -119 |
| 2004-07-15 | vs MIN | 86 | W 3-1 | 32-54 | 5 | 18,540 | Zack Greinke | Kyle Lohse | Zack Greinke | Kyle Lohse | Ryan Bukvich | 363 | 480 | -117 |
| 2004-07-16 | vs MIN | 87 | W 12-3 | 33-54 | 5 | 25,189 | Darrell May | Brad Radke | Darrell May | Brad Radke | | 375 | 483 | -108 |
| 2004-07-17 | vs MIN | 88 | L 1-4 | 33-55 | 5 | 30,094 | Jimmy Gobble | Johan Santana | Johan Santana | Jimmy Gobble | Joe Nathan | 376 | 487 | -111 |
| 2004-07-18 | vs MIN | 89 | W 4-3 | 34-55 | 5 | 20,099 | Mike Wood | Carlos Silva | Dennys Reyes | Grant Balfour | | 380 | 490 | -110 |
| 2004-07-19 | vs BAL | 90 | L 4-7 | 34-56 | 5 | 17,586 | Brian Anderson | Sidney Ponson | Sidney Ponson | Brian Anderson | | 384 | 497 | -113 |
| 2004-07-20 | vs BAL | 91 | L 3-12 | 34-57 | 5 | 18,225 | Zack Greinke | Daniel Cabrera | Daniel Cabrera | Zack Greinke | | 387 | 509 | -122 |
| 2004-07-21 | @ DET | 92 | L 2-4 | 34-58 | 5 | 17,607 | Darrell May | Mike Maroth | Mike Maroth | Darrell May | Jamie Walker | 389 | 513 | -124 |
| 2004-07-22 | @ DET | 93 | W 13-7 | 35-58 | 5 | 24,746 | Jimmy Gobble | Gary Knotts | Jimmy Gobble | Gary Knotts | | 402 | 520 | -118 |
| 2004-07-23 | @ CLE | 94 | L 2-3 | 35-59 | 5 | 26,504 | Mike Wood | Scott Elarton | Rick White | Nate Field | | 404 | 523 | -119 |
| 2004-07-24 | @ CLE | 95 | L 2-10 | 35-61 | 5 | 18,873 | Chris George | Chad Durbin | Chad Durbin | Chris George | | 406 | 533 | -127 |
| 2004-07-24 | @ CLE | 96 | L 3-4 | 35-61 | 5 | 27,865 | Brian Anderson | Kazuhito Tadano | Matt Miller | Scott Sullivan | | 409 | 537 | -128 |
| 2004-07-25 | @ CLE | 97 | L 1-5 | 35-62 | 5 | 23,540 | Zack Greinke | Jake Westbrook | Jake Westbrook | Zack Greinke | | 410 | 542 | -132 |
| 2004-07-27 | @ TBA | 98 | L 2-6 | 35-63 | 5 | 10,854 | Darrell May | Dewon Brazelton | Dewon Brazelton | Darrell May | | 412 | 548 | -136 |
| 2004-07-28 | @ TBA | 99 | L 1-10 | 35-64 | 5 | 10,555 | Jimmy Gobble | Mark Hendrickson | Mark Hendrickson | Jimmy Gobble | | 413 | 558 | -145 |
| 2004-07-29 | @ TBA | 100 | L 0-2 | 35-65 | 5 | 10,084 | Mike Wood | Rob Bell | Rob Bell | Mike Wood | Danys Baez | 413 | 560 | -147 |
| 2004-07-30 | vs CLE | 101 | L 6-7 | 35-66 | 5 | 32,079 | Brian Anderson | Jake Westbrook | Rafael Betancourt | Scott Sullivan | | 419 | 567 | -148 |
| 2004-07-31 | vs CLE | 102 | W 10-3 | 36-66 | 5 | 27,689 | Zack Greinke | Kazuhito Tadano | Zack Greinke | Kazuhito Tadano | | 429 | 570 | -141 |
| 2004-08-01 | vs CLE | 103 | W 8-7 | 37-66 | 5 | 15,641 | Darrell May | CC Sabathia | Darrell May | CC Sabathia | Shawn Camp | 437 | 577 | -140 |
| 2004-08-03 | vs CHA | 104 | L 4-12 | 37-67 | 5 | 13,981 | Mike Wood | Jose Contreras | Jose Contreras | Mike Wood | | 441 | 589 | -148 |
| 2004-08-04 | vs CHA | 105 | W 11-0 | 38-67 | 5 | 16,194 | Brian Anderson | Scott Schoeneweis | Brian Anderson | Scott Schoeneweis | | 452 | 589 | -137 |
| 2004-08-05 | vs CHA | 106 | W 6-4 | 39-67 | 5 | 15,863 | Zack Greinke | Jon Garland | Zack Greinke | Jon Garland | Nate Field | 458 | 593 | -135 |
| 2004-08-06 | vs ANA | 107 | L 0-3 | 39-68 | 5 | 20,572 | Darrell May | Kelvim Escobar | Kelvim Escobar | Darrell May | Troy Percival | 458 | 596 | -138 |
| 2004-08-07 | vs ANA | 108 | L 5-7 | 39-69 | 5 | 27,046 | Jimmy Serrano | Bartolo Colon | Bartolo Colon | Dennys Reyes | Troy Percival | 463 | 603 | -140 |
| 2004-08-08 | vs ANA | 109 | L 4-6 | 39-70 | 5 | 18,366 | Mike Wood | John Lackey | Brendan Donnelly | Nate Field | Francisco Rodriguez | 467 | 609 | -142 |
| 2004-08-09 | vs ANA | 110 | L 3-5 | 39-71 | 5 | 16,262 | Brian Anderson | Ramon Ortiz | Kevin Gregg | Jaime Cerda | Troy Percival | 470 | 614 | -144 |
| 2004-08-10 | @ CHA | 111 | L 3-9 | 39-72 | 5 | 20,506 | Zack Greinke | Jon Garland | Jon Garland | Zack Greinke | | 473 | 623 | -150 |
| 2004-08-11 | @ CHA | 112 | W 4-2 | 40-72 | 5 | 18,396 | Darrell May | Mark Buehrle | Darrell May | Mark Buehrle | Jaime Cerda | 477 | 625 | -148 |
| 2004-08-12 | @ CHA | 113 | L 2-3 | 40-73 | 5 | 22,399 | Jimmy Serrano | Freddy Garcia | Freddy Garcia | Jimmy Serrano | Shingo Takatsu | 479 | 628 | -149 |
| 2004-08-13 | @ OAK | 114 | W 10-3 | 41-73 | 5 | 24,091 | Mike Wood | Mark Mulder | Mike Wood | Mark Mulder | | 489 | 631 | -142 |
| 2004-08-14 | @ OAK | 115 | L 1-6 | 41-74 | 5 | 36,942 | Brian Anderson | Rich Harden | Rich Harden | Brian Anderson | | 490 | 637 | -147 |
| 2004-08-15 | @ OAK | 116 | W 6-1 | 42-74 | 5 | 37,748 | Zack Greinke | Barry Zito | Zack Greinke | Barry Zito | | 496 | 638 | -142 |
| 2004-08-17 | vs SEA | 117 | L 3-16 | 42-75 | 5 | 20,341 | Darrell May | Bobby Madritsch | Bobby Madritsch | Darrell May | | 499 | 654 | -155 |
| 2004-08-18 | vs SEA | 118 | W 3-2 | 43-75 | 5 | 19,653 | Jimmy Serrano | Ryan Franklin | D.J. Carrasco | Ryan Franklin | | 502 | 656 | -154 |
| 2004-08-20 | vs TEX | 119 | L 3-5 | 43-76 | 5 | 17,385 | Mike Wood | Ryan Drese | Ryan Drese | Mike Wood | Francisco Cordero | 505 | 661 | -156 |
| 2004-08-21 | vs TEX | 120 | L 3-5 | 43-77 | 5 | 25,035 | Brian Anderson | Mickey Callaway | Frank Francisco | Brian Anderson | Francisco Cordero | 508 | 666 | -158 |
| 2004-08-22 | vs TEX | 121 | W 10-2 | 44-77 | 5 | 22,286 | Zack Greinke | Scott Erickson | Zack Greinke | Scott Erickson | | 518 | 668 | -150 |
| 2004-08-23 | @ ANA | 122 | L 4-9 | 44-78 | 5 | 40,717 | Darrell May | Bartolo Colon | Bartolo Colon | Darrell May | | 522 | 677 | -155 |
| 2004-08-24 | @ ANA | 123 | L 5-7 | 44-79 | 5 | 40,183 | Jimmy Serrano | John Lackey | John Lackey | Dennys Reyes | Troy Percival | 527 | 684 | -157 |
| 2004-08-25 | @ ANA | 124 | L 6-21 | 44-80 | 5 | 39,657 | Mike Wood | Ramon Ortiz | Ramon Ortiz | Mike Wood | | 533 | 705 | -172 |
| 2004-08-26 | @ SEA | 125 | W 7-3 | 45-80 | 5 | 30,962 | Brian Anderson | Jamie Moyer | Brian Anderson | Jamie Moyer | | 540 | 708 | -168 |
| 2004-08-27 | @ SEA | 126 | L 5-7 | 45-81 | 5 | 35,690 | Zack Greinke | Gil Meche | George Sherrill | D.J. Carrasco | J.J. Putz | 545 | 715 | -170 |
| 2004-08-28 | @ SEA | 127 | L 7-9 | 45-83 | 5 | 0 | Darrell May | Clint Nageotte | Matt Thornton | Darrell May | J.J. Putz | 552 | 724 | -172 |
| 2004-08-28 | @ SEA | 128 | L 3-5 | 45-83 | 5 | 41,362 | Jimmy Serrano | Bobby Madritsch | Cha-Seung Baek | Matt Kinney | | 555 | 729 | -174 |
| 2004-08-29 | @ SEA | 129 | L 4-5 | 45-84 | 5 | 37,141 | Jimmy Gobble | Ryan Franklin | Ron Villone | Dennys Reyes | | 559 | 734 | -175 |
| 2004-08-30 | vs DET | 130 | L 1-9 | 45-85 | 5 | 19,429 | Mike Wood | Nate Robertson | Nate Robertson | Mike Wood | | 560 | 743 | -183 |
| 2004-08-31 | vs DET | 131 | W 9-8 | 46-85 | 5 | 19,471 | Brian Anderson | Jason Johnson | Jeremy Affeldt | Ugueth Urbina | | 569 | 751 | -182 |
| 2004-09-01 | vs DET | 132 | W 1-0 | 47-85 | 5 | 19,039 | Zack Greinke | Mike Maroth | Zack Greinke | Mike Maroth | Jeremy Affeldt | 570 | 751 | -181 |
| 2004-09-03 | @ MIN | 133 | L 0-2 | 47-86 | 5 | 22,239 | Darrell May | Johan Santana | Johan Santana | Darrell May | Joe Nathan | 570 | 753 | -183 |
| 2004-09-04 | @ MIN | 134 | L 3-4 | 47-87 | 5 | 23,735 | Mike Wood | Carlos Silva | J.C. Romero | Dennys Reyes | | 573 | 757 | -184 |
| 2004-09-05 | @ MIN | 135 | W 12-3 | 48-87 | 5 | 33,885 | Jimmy Gobble | Kyle Lohse | Jimmy Gobble | Kyle Lohse | | 585 | 760 | -175 |
| 2004-09-06 | @ DET | 136 | L 3-7 | 48-88 | 5 | 21,516 | Denny Bautista | Wil Ledezma | Wil Ledezma | Denny Bautista | Gary Knotts | 588 | 767 | -179 |
| 2004-09-07 | @ DET | 137 | W 6-2 | 49-88 | 5 | 17,462 | Brian Anderson | Nate Robertson | Jimmy Serrano | Nate Robertson | | 594 | 769 | -175 |
| 2004-09-09 | @ DET | 138 | W 26-5 | 50-89 | 5 | 0 | Zack Greinke | Jason Johnson | Zack Greinke | Jason Johnson | | 620 | 774 | -154 |
| 2004-09-09 | @ DET | 139 | L 0-8 | 50-89 | 5 | 20,442 | Darrell May | Jeremy Bonderman | Jeremy Bonderman | Darrell May | | 620 | 782 | -162 |
| 2004-09-10 | vs TBA | 140 | W 8-5 | 51-89 | 5 | 17,746 | Mike Wood | Mark Hendrickson | Dennys Reyes | Franklin Nunez | Jeremy Affeldt | 628 | 787 | -159 |
| 2004-09-11 | vs TBA | 141 | L 6-8 | 51-90 | 5 | 17,496 | Jimmy Gobble | Doug Waechter | Rob Bell | Jimmy Serrano | Danys Baez | 634 | 795 | -161 |
| 2004-09-12 | vs TBA | 142 | L 2-7 | 51-91 | 5 | 14,015 | Denny Bautista | Jorge Sosa | Jorge Sosa | Denny Bautista | | 636 | 802 | -166 |
| 2004-09-13 | vs NYA | 143 | W 17-8 | 52-91 | 5 | 23,951 | Brian Anderson | Brad Halsey | Brian Anderson | Brad Halsey | | 653 | 810 | -157 |
| 2004-09-14 | vs NYA | 144 | L 0-4 | 52-92 | 5 | 23,426 | Zack Greinke | Mike Mussina | Mike Mussina | Zack Greinke | | 653 | 814 | -161 |
| 2004-09-15 | vs NYA | 145 | L 0-3 | 52-93 | 5 | 22,418 | Darrell May | Javier Vazquez | Javier Vazquez | Darrell May | Mariano Rivera | 653 | 817 | -164 |
| 2004-09-17 | @ CLE | 146 | W 6-4 | 53-93 | 5 | 14,347 | Mike Wood | Jake Westbrook | Mike Wood | Jake Westbrook | Jeremy Affeldt | 659 | 821 | -162 |
| 2004-09-18 | @ CLE | 147 | W 7-1 | 54-93 | 5 | 17,848 | Jimmy Gobble | Cliff Lee | Jimmy Gobble | Cliff Lee | | 666 | 822 | -156 |
| 2004-09-19 | @ CLE | 148 | L 3-8 | 54-94 | 5 | 16,745 | Denny Bautista | Kyle Denney | Kyle Denney | Denny Bautista | | 669 | 830 | -161 |
| 2004-09-20 | @ TBA | 149 | W 6-3 | 55-94 | 5 | 8,315 | Brian Anderson | Dewon Brazelton | Brian Anderson | Jorge Sosa | Jeremy Affeldt | 675 | 833 | -158 |
| 2004-09-21 | @ TBA | 150 | L 4-7 | 55-95 | 5 | 8,588 | Zack Greinke | Rob Bell | Mark Hendrickson | Shawn Camp | Danys Baez | 679 | 840 | -161 |
| 2004-09-22 | @ TBA | 151 | W 7-6 | 56-95 | 5 | 8,392 | Darrell May | Doug Waechter | Mike MacDougal | Jorge Sosa | Jeremy Affeldt | 686 | 846 | -160 |
| 2004-09-23 | @ CHA | 152 | L 6-7 | 56-96 | 5 | 16,015 | Mike Wood | Jose Contreras | Damaso Marte | Jeremy Affeldt | | 692 | 853 | -161 |
| 2004-09-24 | @ CHA | 153 | W 8-6 | 57-96 | 5 | 14,270 | Jimmy Gobble | Freddy Garcia | Jimmy Gobble | Felix Diaz | | 700 | 859 | -159 |
| 2004-09-25 | @ CHA | 154 | L 1-5 | 57-97 | 5 | 20,625 | Denny Bautista | Mark Buehrle | Mark Buehrle | Denny Bautista | | 701 | 864 | -163 |
| 2004-09-26 | @ CHA | 155 | L 1-5 | 57-98 | 5 | 18,949 | Brian Anderson | Jon Garland | Jon Garland | Brian Anderson | Damaso Marte | 702 | 869 | -167 |
| 2004-09-27 | vs CLE | 156 | L 1-6 | 57-99 | 5 | 11,544 | Zack Greinke | Jake Westbrook | Jake Westbrook | Jaime Cerda | | 703 | 875 | -172 |
| 2004-09-28 | vs CLE | 157 | L 1-5 | 57-100 | 5 | 11,847 | Darrell May | Cliff Lee | Cliff Lee | Darrell May | | 704 | 880 | -176 |
| 2004-09-29 | vs CLE | 158 | L 2-5 | 57-101 | 5 | 11,193 | Mike Wood | Kyle Denney | Cliff Bartosh | Mike Wood | Bob Wickman | 706 | 885 | -179 |
| 2004-09-30 | vs CHA | 159 | L 2-9 | 57-102 | 5 | 11,507 | Chris George | Mark Buehrle | Mark Buehrle | Shawn Camp | | 708 | 894 | -186 |
| 2004-10-01 | vs CHA | 160 | L 2-4 | 57-103 | 5 | 14,766 | Denny Bautista | Jon Garland | Jon Garland | Jaime Cerda | Shingo Takatsu | 710 | 898 | -188 |
| 2004-10-02 | vs CHA | 161 | W 10-2 | 58-103 | 5 | 16,028 | Brian Anderson | Jason Grilli | Brian Anderson | Jason Grilli | | 720 | 900 | -180 |
| 2004-10-03 | vs CHA | 162 | L 0-5 | 58-104 | 5 | 14,586 | Zack Greinke | Jose Contreras | Jose Contreras | Zack Greinke | | 720 | 905 | -185 |