| 2004-04-06 | vs COL | 1 | L 2-6 | 0-1 | 5 | 46,949 | Randy Johnson | Shawn Estes | Shawn Estes | Randy Johnson | | 2 | 6 | -4 |
| 2004-04-07 | vs COL | 2 | W 9-5 | 1-1 | 3 | 25,918 | Brandon Webb | Jason Jennings | Brandon Webb | Jason Jennings | Matt Mantei | 11 | 11 | 0 |
| 2004-04-08 | vs COL | 3 | W 6-5 | 2-1 | 1 | 26,448 | Elmer Dessens | Joe Kennedy | Steve Randolph | Shawn Chacon | | 17 | 16 | 1 |
| 2004-04-09 | vs SLN | 4 | L 6-13 | 2-2 | 2 | 35,930 | Casey Daigle | Chris Carpenter | Chris Carpenter | Casey Daigle | | 23 | 29 | -6 |
| 2004-04-10 | vs SLN | 5 | L 2-10 | 2-3 | 3 | 38,842 | Steve Sparks | Matt Morris | Matt Morris | Steve Sparks | | 25 | 39 | -14 |
| 2004-04-11 | vs SLN | 6 | L 5-6 | 2-4 | 4 | 32,072 | Randy Johnson | Jason Marquis | Mike Lincoln | Matt Mantei | Jason Isringhausen | 30 | 45 | -15 |
| 2004-04-12 | @ COL | 7 | L 4-7 | 2-5 | 5 | 48,013 | Brandon Webb | Jason Jennings | Vladimir Nunez | Mike Koplove | Shawn Chacon | 34 | 52 | -18 |
| 2004-04-14 | @ COL | 8 | L 4-14 | 2-6 | 5 | 23,128 | Elmer Dessens | Joe Kennedy | Joe Kennedy | Elmer Dessens | | 38 | 66 | -28 |
| 2004-04-15 | @ COL | 9 | W 11-10 | 3-6 | 5 | 22,320 | Casey Daigle | Scott Elarton | Mike Koplove | Scott Elarton | Matt Mantei | 49 | 76 | -27 |
| 2004-04-16 | @ SDN | 10 | W 5-0 | 4-6 | 3 | 37,300 | Randy Johnson | Jake Peavy | Randy Johnson | Jake Peavy | | 54 | 76 | -22 |
| 2004-04-17 | @ SDN | 11 | L 2-3 | 4-7 | 4 | 42,261 | Brandon Webb | Ismael Valdez | Ismael Valdez | Brandon Webb | Trevor Hoffman | 56 | 79 | -23 |
| 2004-04-18 | @ SDN | 12 | L 5-6 | 4-8 | 5 | 41,730 | Steve Sparks | Adam Eaton | Eddie Oropesa | Matt Mantei | | 61 | 85 | -24 |
| 2004-04-20 | @ MIL | 13 | L 2-4 | 4-9 | 5 | 10,244 | Elmer Dessens | Ben Sheets | Ben Sheets | Elmer Dessens | Danny Kolb | 63 | 89 | -26 |
| 2004-04-21 | @ MIL | 14 | L 6-10 | 4-10 | 5 | 11,223 | Randy Johnson | Doug Davis | Ben Ford | Randy Johnson | | 69 | 99 | -30 |
| 2004-04-22 | @ MIL | 15 | W 11-9 | 5-10 | 5 | 13,879 | Brandon Webb | Wes Obermueller | Steve Sparks | Adrian Hernandez | | 80 | 108 | -28 |
| 2004-04-23 | vs SDN | 16 | W 5-2 | 6-10 | 4 | 30,028 | Casey Daigle | Adam Eaton | Mike Koplove | Adam Eaton | Matt Mantei | 85 | 110 | -25 |
| 2004-04-24 | vs SDN | 17 | L 2-4 | 6-11 | 5 | 32,657 | Steve Sparks | David Wells | Akinori Otsuka | Oscar Villarreal | Trevor Hoffman | 87 | 114 | -27 |
| 2004-04-25 | vs SDN | 18 | W 12-7 | 7-11 | 4 | 32,553 | Elmer Dessens | Brian Lawrence | Elmer Dessens | Brian Lawrence | | 99 | 121 | -22 |
| 2004-04-26 | vs CHN | 19 | W 9-0 | 8-11 | 3 | 33,564 | Randy Johnson | Carlos Zambrano | Randy Johnson | Carlos Zambrano | | 108 | 121 | -13 |
| 2004-04-27 | vs CHN | 20 | W 10-1 | 9-11 | 3 | 33,781 | Brandon Webb | Sergio Mitre | Brandon Webb | Sergio Mitre | | 118 | 122 | -4 |
| 2004-04-28 | vs CHN | 21 | L 3-4 | 9-12 | 3 | 34,761 | Casey Daigle | Greg Maddux | LaTroy Hawkins | Matt Mantei | Joe Borowski | 121 | 126 | -5 |
| 2004-04-30 | @ PHI | 22 | L 0-4 | 9-13 | 5 | 43,721 | Elmer Dessens | Randy Wolf | Randy Wolf | Elmer Dessens | | 121 | 130 | -9 |
| 2004-05-01 | @ PHI | 23 | W 6-4 | 10-13 | 4 | 44,048 | Randy Johnson | Vicente Padilla | Randy Johnson | Vicente Padilla | Matt Mantei | 127 | 134 | -7 |
| 2004-05-02 | @ PHI | 24 | L 5-6 | 10-14 | 5 | 43,025 | Brandon Webb | Eric Milton | Ryan Madson | Oscar Villarreal | | 132 | 140 | -8 |
| 2004-05-04 | @ CHN | 25 | W 6-3 | 11-14 | 4 | 38,942 | Steve Sparks | Sergio Mitre | Steve Sparks | Sergio Mitre | Jose Valverde | 138 | 143 | -5 |
| 2004-05-05 | @ CHN | 26 | W 2-0 | 12-14 | 3 | 38,902 | Casey Daigle | Kerry Wood | Casey Daigle | Kerry Wood | Jose Valverde | 140 | 143 | -3 |
| 2004-05-06 | @ CHN | 27 | L 3-11 | 12-15 | 3 | 38,169 | Elmer Dessens | Matt Clement | Matt Clement | Elmer Dessens | | 143 | 154 | -11 |
| 2004-05-07 | vs PHI | 28 | L 1-4 | 12-16 | 4 | 30,738 | Randy Johnson | Vicente Padilla | Vicente Padilla | Randy Johnson | Billy Wagner | 144 | 158 | -14 |
| 2004-05-08 | vs PHI | 29 | L 7-8 | 12-17 | 5 | 38,907 | Brandon Webb | Eric Milton | Eric Milton | Brandon Webb | Tim Worrell | 151 | 166 | -15 |
| 2004-05-09 | vs PHI | 30 | L 1-7 | 12-18 | 5 | 29,637 | Steve Sparks | Brett Myers | Brett Myers | Steve Sparks | | 152 | 173 | -21 |
| 2004-05-10 | vs NYN | 31 | W 12-8 | 13-18 | 5 | 28,638 | Casey Daigle | James Baldwin | Casey Daigle | James Baldwin | | 164 | 181 | -17 |
| 2004-05-11 | vs NYN | 32 | W 9-5 | 14-18 | 3 | 34,263 | Elmer Dessens | Al Leiter | Brian Bruney | Al Leiter | | 173 | 186 | -13 |
| 2004-05-12 | vs NYN | 33 | L 0-1 | 14-19 | 4 | 27,750 | Randy Johnson | Tom Glavine | Tom Glavine | Randy Johnson | Braden Looper | 173 | 187 | -14 |
| 2004-05-13 | vs NYN | 34 | L 4-7 | 14-20 | 5 | 25,573 | Brandon Webb | Jae Weong Seo | Jae Weong Seo | Brandon Webb | Braden Looper | 177 | 194 | -17 |
| 2004-05-14 | vs MON | 35 | L 3-4 | 14-21 | 5 | 27,118 | Casey Fossum | Tomo Ohka | Chad Cordero | Jose Valverde | Rocky Biddle | 180 | 198 | -18 |
| 2004-05-15 | vs MON | 36 | L 0-5 | 14-22 | 5 | 32,379 | Casey Daigle | Claudio Vargas | Claudio Vargas | Casey Daigle | | 180 | 203 | -23 |
| 2004-05-16 | vs MON | 37 | L 1-6 | 14-23 | 5 | 32,629 | Steve Sparks | Livan Hernandez | Livan Hernandez | Steve Sparks | | 181 | 209 | -28 |
| 2004-05-18 | @ ATL | 38 | W 2-0 | 15-23 | 5 | 23,381 | Randy Johnson | Mike Hampton | Randy Johnson | Mike Hampton | | 183 | 209 | -26 |
| 2004-05-19 | @ ATL | 39 | W 6-4 | 16-23 | 4 | 19,971 | Brandon Webb | John Thomson | Brian Bruney | Armando Almanza | | 189 | 213 | -24 |
| 2004-05-20 | @ ATL | 40 | L 1-5 | 16-24 | 5 | 21,044 | Casey Fossum | Horacio Ramirez | Horacio Ramirez | Casey Fossum | | 190 | 218 | -28 |
| 2004-05-21 | @ FLO | 41 | L 5-6 | 16-25 | 5 | 17,368 | Casey Daigle | Darren Oliver | Armando Benitez | Brian Bruney | | 195 | 224 | -29 |
| 2004-05-22 | @ FLO | 42 | L 2-11 | 16-26 | 5 | 25,174 | Steve Sparks | Brad Penny | Brad Penny | Steve Sparks | | 197 | 235 | -38 |
| 2004-05-23 | @ FLO | 43 | W 4-3 | 17-26 | 4 | 40,819 | Randy Johnson | Dontrelle Willis | Randy Johnson | Dontrelle Willis | Jose Valverde | 201 | 238 | -37 |
| 2004-05-24 | @ FLO | 44 | L 5-13 | 17-27 | 5 | 10,214 | Brandon Webb | Carl Pavano | Carl Pavano | Brandon Webb | | 206 | 251 | -45 |
| 2004-05-25 | @ SFN | 45 | L 1-4 | 17-28 | 5 | 36,664 | Casey Fossum | Jason Schmidt | Jason Schmidt | Casey Fossum | Matt Herges | 207 | 255 | -48 |
| 2004-05-26 | @ SFN | 46 | L 3-4 | 17-29 | 5 | 38,187 | Casey Daigle | Kirk Rueter | Felix Rodriguez | Brian Bruney | Matt Herges | 210 | 259 | -49 |
| 2004-05-27 | @ SFN | 47 | L 4-5 | 17-30 | 5 | 36,122 | Steve Sparks | Dustin Hermanson | Tyler Walker | Jose Valverde | | 214 | 264 | -50 |
| 2004-05-28 | @ LAN | 48 | W 6-3 | 18-30 | 5 | 46,455 | Randy Johnson | Wilson Alvarez | Randy Johnson | Wilson Alvarez | Elmer Dessens | 220 | 267 | -47 |
| 2004-05-29 | @ LAN | 49 | L 0-10 | 18-31 | 5 | 35,343 | Brandon Webb | Jose Lima | Jose Lima | Brandon Webb | | 220 | 277 | -57 |
| 2004-05-30 | @ LAN | 50 | L 0-3 | 18-32 | 5 | 41,060 | Casey Fossum | Kazuhisa Ishii | Kazuhisa Ishii | Casey Fossum | Eric Gagne | 220 | 280 | -60 |
| 2004-05-31 | vs SFN | 51 | L 4-8 | 18-33 | 5 | 35,449 | Casey Daigle | Kirk Rueter | Kirk Rueter | Casey Daigle | | 224 | 288 | -64 |
| 2004-06-01 | vs SFN | 52 | W 6-5 | 19-33 | 5 | 32,178 | Steve Sparks | Dustin Hermanson | Jose Valverde | Jason Christiansen | | 230 | 293 | -63 |
| 2004-06-02 | vs SFN | 53 | W 8-6 | 20-33 | 5 | 27,897 | Randy Johnson | Brett Tomko | Randy Johnson | Brett Tomko | Jose Valverde | 238 | 299 | -61 |
| 2004-06-03 | vs SFN | 54 | W 11-5 | 21-33 | 4 | 25,086 | Brandon Webb | Jerome Williams | Brandon Webb | Jerome Williams | | 249 | 304 | -55 |
| 2004-06-04 | vs LAN | 55 | L 3-7 | 21-34 | 4 | 32,182 | Casey Fossum | Kazuhisa Ishii | Kazuhisa Ishii | Casey Fossum | Guillermo Mota | 252 | 311 | -59 |
| 2004-06-05 | vs LAN | 56 | L 3-10 | 21-35 | 5 | 42,407 | Edgar Gonzalez | Odalis Perez | Odalis Perez | Edgar Gonzalez | | 255 | 321 | -66 |
| 2004-06-06 | vs LAN | 57 | W 6-5 | 22-35 | 4 | 34,059 | Steve Sparks | Jeff Weaver | Scott Service | Darren Dreifort | Jose Valverde | 261 | 326 | -65 |
| 2004-06-08 | @ BAL | 58 | W 8-1 | 23-35 | 4 | 28,927 | Randy Johnson | Sidney Ponson | Randy Johnson | Sidney Ponson | | 269 | 327 | -58 |
| 2004-06-09 | @ BAL | 59 | L 2-8 | 23-36 | 4 | 25,776 | Brandon Webb | Eric DuBose | John Parrish | Steve Randolph | | 271 | 335 | -64 |
| 2004-06-10 | @ BAL | 60 | W 3-0 | 24-36 | 4 | 25,106 | Casey Fossum | Daniel Cabrera | Casey Fossum | Daniel Cabrera | Jose Valverde | 274 | 335 | -61 |
| 2004-06-11 | @ TOR | 61 | W 3-2 | 25-36 | 4 | 14,259 | Steve Sparks | Pat Hentgen | Randy Choate | Jason Frasor | Jose Valverde | 277 | 337 | -60 |
| 2004-06-12 | @ TOR | 62 | L 4-15 | 25-37 | 4 | 30,349 | Andrew Good | Roy Halladay | Roy Halladay | Andrew Good | Vinnie Chulk | 281 | 352 | -71 |
| 2004-06-13 | @ TOR | 63 | W 5-3 | 26-37 | 4 | 22,766 | Randy Johnson | Ted Lilly | Randy Johnson | Ted Lilly | Jose Valverde | 286 | 355 | -69 |
| 2004-06-15 | vs NYA | 64 | L 2-4 | 26-38 | 4 | 48,066 | Brandon Webb | Jose Contreras | Jose Contreras | Brandon Webb | Mariano Rivera | 288 | 359 | -71 |
| 2004-06-16 | vs NYA | 65 | L 4-9 | 26-39 | 4 | 48,274 | Casey Fossum | Tanyon Sturtze | Tanyon Sturtze | Casey Fossum | | 292 | 368 | -76 |
| 2004-06-17 | vs NYA | 66 | W 6-1 | 27-39 | 4 | 48,252 | Steve Sparks | Jon Lieber | Steve Sparks | Jon Lieber | Elmer Dessens | 298 | 369 | -71 |
| 2004-06-18 | vs TBA | 67 | L 2-6 | 27-40 | 4 | 27,995 | Randy Johnson | John Halama | John Halama | Randy Johnson | | 300 | 375 | -75 |
| 2004-06-19 | vs TBA | 68 | L 4-11 | 27-41 | 4 | 29,440 | Lance Cormier | Dewon Brazelton | Rob Bell | Lance Cormier | | 304 | 386 | -82 |
| 2004-06-20 | vs TBA | 69 | L 1-2 | 27-42 | 4 | 36,037 | Brandon Webb | Mark Hendrickson | Mark Hendrickson | Brandon Webb | Jesus Colome | 305 | 388 | -83 |
| 2004-06-21 | @ SDN | 70 | L 1-3 | 27-43 | 4 | 29,253 | Casey Fossum | Ismael Valdez | Ismael Valdez | Casey Fossum | Trevor Hoffman | 306 | 391 | -85 |
| 2004-06-22 | @ SDN | 71 | L 1-2 | 27-44 | 4 | 30,933 | Steve Sparks | Adam Eaton | Trevor Hoffman | Mike Koplove | | 307 | 393 | -86 |
| 2004-06-23 | @ SDN | 72 | L 3-4 | 27-45 | 4 | 37,304 | Randy Johnson | David Wells | Akinori Otsuka | Elmer Dessens | | 310 | 397 | -87 |
| 2004-06-25 | @ DET | 73 | L 1-2 | 27-46 | 5 | 32,573 | Brandon Webb | Jason Johnson | Jason Johnson | Brandon Webb | Ugueth Urbina | 311 | 399 | -88 |
| 2004-06-26 | @ DET | 74 | L 6-7 | 27-47 | 5 | 33,579 | Casey Fossum | Jeremy Bonderman | Ugueth Urbina | Brandon Villafuerte | | 317 | 406 | -89 |
| 2004-06-27 | @ DET | 75 | L 5-9 | 27-48 | 5 | 32,751 | Steve Sparks | Mike Maroth | Jamie Walker | Brandon Villafuerte | | 322 | 415 | -93 |
| 2004-06-28 | vs SDN | 76 | L 5-10 | 27-49 | 5 | 29,411 | Shane Reynolds | David Wells | David Wells | Shane Reynolds | | 327 | 425 | -98 |
| 2004-06-29 | vs SDN | 77 | L 2-3 | 27-50 | 5 | 34,633 | Randy Johnson | Brian Sweeney | Brian Sweeney | Randy Johnson | Trevor Hoffman | 329 | 428 | -99 |
| 2004-06-30 | vs SDN | 78 | W 8-5 | 28-50 | 5 | 24,275 | Brandon Webb | Brian Lawrence | Steve Randolph | Blaine Neal | Mike Koplove | 337 | 433 | -96 |
| 2004-07-01 | vs SDN | 79 | W 7-5 | 29-50 | 4 | 22,631 | Casey Fossum | Ismael Valdez | Casey Fossum | Ismael Valdez | Mike Koplove | 344 | 438 | -94 |
| 2004-07-02 | vs MIN | 80 | L 5-6 | 29-51 | 5 | 27,045 | Steve Sparks | Kyle Lohse | J.C. Romero | Steve Randolph | Joe Nathan | 349 | 444 | -95 |
| 2004-07-03 | vs MIN | 81 | L 4-8 | 29-52 | 5 | 29,830 | Andrew Good | Terry Mulholland | Terry Mulholland | Andrew Good | Juan Rincon | 353 | 452 | -99 |
| 2004-07-04 | vs MIN | 82 | W 6-2 | 30-52 | 5 | 31,732 | Randy Johnson | Carlos Silva | Randy Johnson | Carlos Silva | | 359 | 454 | -95 |
| 2004-07-05 | @ LAN | 83 | L 5-6 | 30-53 | 5 | 32,929 | Brandon Webb | Wilson Alvarez | Giovanni Carrara | Brandon Villafuerte | | 364 | 460 | -96 |
| 2004-07-06 | @ LAN | 84 | L 1-4 | 30-54 | 5 | 25,139 | Casey Fossum | Jose Lima | Jose Lima | Casey Fossum | Eric Gagne | 365 | 464 | -99 |
| 2004-07-07 | @ LAN | 85 | L 0-11 | 30-55 | 5 | 27,899 | Steve Sparks | Kazuhisa Ishii | Kazuhisa Ishii | Steve Sparks | | 365 | 475 | -110 |
| 2004-07-08 | @ SFN | 86 | W 8-4 | 31-55 | 5 | 38,194 | Elmer Dessens | Dustin Hermanson | Andrew Good | Dustin Hermanson | | 373 | 479 | -106 |
| 2004-07-09 | @ SFN | 87 | L 3-8 | 31-56 | 5 | 41,110 | Randy Johnson | Jerome Williams | Jerome Williams | Randy Johnson | | 376 | 487 | -111 |
| 2004-07-10 | @ SFN | 88 | L 1-3 | 31-57 | 5 | 42,621 | Brandon Webb | Brett Tomko | Brett Tomko | Brandon Webb | Matt Herges | 377 | 490 | -113 |
| 2004-07-11 | @ SFN | 89 | L 2-9 | 31-58 | 5 | 42,558 | Casey Fossum | Jason Schmidt | Jason Schmidt | Casey Fossum | | 379 | 499 | -120 |
| 2004-07-15 | vs LAN | 90 | L 3-4 | 31-59 | 5 | 28,150 | Randy Johnson | Jeff Weaver | Wilson Alvarez | Randy Choate | Eric Gagne | 382 | 503 | -121 |
| 2004-07-16 | vs LAN | 91 | L 2-6 | 31-60 | 5 | 29,255 | Brandon Webb | Kazuhisa Ishii | Kazuhisa Ishii | Brandon Webb | | 384 | 509 | -125 |
| 2004-07-17 | vs LAN | 92 | L 6-7 | 31-61 | 5 | 37,027 | Casey Fossum | Odalis Perez | Guillermo Mota | Brian Bruney | Eric Gagne | 390 | 516 | -126 |
| 2004-07-18 | vs LAN | 93 | L 3-10 | 31-62 | 5 | 29,131 | Elmer Dessens | Jose Lima | Jose Lima | Elmer Dessens | | 393 | 526 | -133 |
| 2004-07-19 | vs SFN | 94 | L 1-6 | 31-63 | 5 | 31,624 | Steve Sparks | Brett Tomko | Brett Tomko | Steve Sparks | | 394 | 532 | -138 |
| 2004-07-20 | vs SFN | 95 | L 1-3 | 31-64 | 5 | 33,743 | Randy Johnson | Jerome Williams | Jerome Williams | Randy Johnson | Jason Christiansen | 395 | 535 | -140 |
| 2004-07-21 | vs HOU | 96 | L 2-5 | 31-65 | 5 | 26,907 | Brandon Webb | Andy Pettitte | Andy Pettitte | Brandon Webb | Brad Lidge | 397 | 540 | -143 |
| 2004-07-22 | vs HOU | 97 | L 3-10 | 31-66 | 5 | 26,003 | Edgar Gonzalez | Roy Oswalt | Roy Oswalt | Edgar Gonzalez | | 400 | 550 | -150 |
| 2004-07-23 | vs COL | 98 | L 2-8 | 31-67 | 5 | 26,350 | Casey Fossum | Jeff Fassero | Jeff Fassero | Casey Fossum | | 402 | 558 | -156 |
| 2004-07-24 | vs COL | 99 | L 2-8 | 31-68 | 5 | 31,409 | Lance Cormier | Jamey Wright | Jamey Wright | Lance Cormier | | 404 | 566 | -162 |
| 2004-07-25 | vs COL | 100 | L 2-3 | 31-69 | 5 | 29,298 | Randy Johnson | Jason Jennings | Jason Jennings | Randy Choate | Shawn Chacon | 406 | 569 | -163 |
| 2004-07-26 | @ HOU | 101 | W 4-1 | 32-69 | 5 | 36,046 | Brandon Webb | Andy Pettitte | Brandon Webb | Andy Pettitte | Greg Aquino | 410 | 570 | -160 |
| 2004-07-27 | @ HOU | 102 | L 3-10 | 32-70 | 5 | 32,095 | Edgar Gonzalez | Roy Oswalt | Roy Oswalt | Edgar Gonzalez | | 413 | 580 | -167 |
| 2004-07-28 | @ HOU | 103 | L 1-6 | 32-71 | 5 | 35,191 | Casey Fossum | Roger Clemens | Roger Clemens | Casey Fossum | | 414 | 586 | -172 |
| 2004-07-29 | @ HOU | 104 | W 6-4 | 33-71 | 5 | 39,758 | Lance Cormier | Tim Redding | Lance Cormier | Tim Redding | Greg Aquino | 420 | 590 | -170 |
| 2004-07-30 | @ COL | 105 | L 1-4 | 33-72 | 5 | 29,436 | Randy Johnson | Jason Jennings | Jason Jennings | Randy Johnson | Shawn Chacon | 421 | 594 | -173 |
| 2004-07-31 | @ COL | 106 | L 4-8 | 33-73 | 5 | 32,392 | Brandon Webb | Shawn Estes | Shawn Estes | Brandon Webb | Shawn Chacon | 425 | 602 | -177 |
| 2004-08-01 | @ COL | 107 | L 2-10 | 33-74 | 5 | 24,193 | Edgar Gonzalez | Aaron Cook | Aaron Cook | Edgar Gonzalez | | 427 | 612 | -185 |
| 2004-08-03 | vs FLO | 108 | W 5-3 | 34-74 | 5 | 28,828 | Casey Fossum | Dontrelle Willis | Mike Koplove | Dontrelle Willis | Greg Aquino | 432 | 615 | -183 |
| 2004-08-04 | vs FLO | 109 | W 11-6 | 35-74 | 5 | 25,045 | Randy Johnson | Josh Beckett | Randy Johnson | Josh Beckett | | 443 | 621 | -178 |
| 2004-08-05 | vs FLO | 110 | L 5-11 | 35-75 | 5 | 24,802 | Lance Cormier | Carl Pavano | Carl Pavano | Lance Cormier | Guillermo Mota | 448 | 632 | -184 |
| 2004-08-06 | vs ATL | 111 | L 2-4 | 35-76 | 5 | 29,368 | Brandon Webb | Jaret Wright | Jaret Wright | Brandon Webb | Chris Reitsma | 450 | 636 | -186 |
| 2004-08-07 | vs ATL | 112 | L 2-6 | 35-77 | 5 | 33,249 | Edgar Gonzalez | Paul Byrd | Paul Byrd | Edgar Gonzalez | | 452 | 642 | -190 |
| 2004-08-08 | vs ATL | 113 | L 4-11 | 35-78 | 5 | 29,601 | Casey Fossum | Russ Ortiz | Russ Ortiz | Casey Fossum | | 456 | 653 | -197 |
| 2004-08-10 | @ MON | 114 | L 0-4 | 35-79 | 5 | 8,386 | Randy Johnson | Livan Hernandez | Livan Hernandez | Randy Johnson | | 456 | 657 | -201 |
| 2004-08-11 | @ MON | 115 | L 3-7 | 35-80 | 5 | 5,089 | Brandon Webb | John Patterson | John Patterson | Brandon Webb | | 459 | 664 | -205 |
| 2004-08-12 | @ MON | 116 | L 5-7 | 35-81 | 5 | 14,639 | Lance Cormier | Rocky Biddle | Luis Ayala | Lance Cormier | Chad Cordero | 464 | 671 | -207 |
| 2004-08-13 | @ NYN | 117 | L 6-10 | 35-82 | 5 | 22,124 | Casey Fossum | Kris Benson | Kris Benson | Casey Fossum | | 470 | 681 | -211 |
| 2004-08-14 | @ NYN | 118 | L 3-4 | 35-83 | 5 | 37,599 | Edgar Gonzalez | Al Leiter | Al Leiter | Edgar Gonzalez | Braden Looper | 473 | 685 | -212 |
| 2004-08-15 | @ NYN | 119 | W 2-0 | 36-83 | 5 | 36,590 | Randy Johnson | Steve Trachsel | Randy Johnson | Steve Trachsel | Greg Aquino | 475 | 685 | -210 |
| 2004-08-16 | vs PIT | 120 | L 7-8 | 36-84 | 5 | 28,768 | Brandon Webb | Sean Burnett | Jose Mesa | Greg Aquino | Mike Gonzalez | 482 | 693 | -211 |
| 2004-08-17 | vs PIT | 121 | L 1-7 | 36-85 | 5 | 30,030 | Steve Randolph | Ryan Vogelsong | Ryan Vogelsong | Steve Randolph | | 483 | 700 | -217 |
| 2004-08-18 | vs PIT | 122 | W 6-3 | 37-85 | 5 | 28,066 | Casey Fossum | John Van Benschoten | Casey Fossum | John Van Benschoten | Greg Aquino | 489 | 703 | -214 |
| 2004-08-20 | vs CIN | 123 | L 0-2 | 37-86 | 5 | 31,998 | Randy Johnson | Luke Hudson | Luke Hudson | Randy Johnson | Joe Valentine | 489 | 705 | -216 |
| 2004-08-21 | vs CIN | 124 | W 2-1 | 38-86 | 5 | 35,102 | Brandon Webb | Aaron Harang | Brandon Webb | Aaron Harang | Greg Aquino | 491 | 706 | -215 |
| 2004-08-22 | vs CIN | 125 | L 1-11 | 38-87 | 5 | 32,198 | Steve Randolph | Brandon Claussen | Brandon Claussen | Steve Randolph | | 492 | 717 | -225 |
| 2004-08-23 | @ PIT | 126 | W 5-4 | 39-87 | 5 | 25,154 | Casey Fossum | John Van Benschoten | Shane Nance | John Grabow | Greg Aquino | 497 | 721 | -224 |
| 2004-08-24 | @ PIT | 127 | L 1-3 | 39-88 | 5 | 16,332 | Edgar Gonzalez | Oliver Perez | Oliver Perez | Edgar Gonzalez | Jose Mesa | 498 | 724 | -226 |
| 2004-08-25 | @ PIT | 128 | L 1-2 | 39-89 | 5 | 24,853 | Randy Johnson | Josh Fogg | Josh Fogg | Randy Johnson | Jose Mesa | 499 | 726 | -227 |
| 2004-08-27 | @ CIN | 129 | W 4-3 | 40-89 | 5 | 23,498 | Brandon Webb | Brandon Claussen | Brian Bruney | Joe Valentine | Greg Aquino | 503 | 729 | -226 |
| 2004-08-28 | @ CIN | 130 | W 6-3 | 41-89 | 5 | 26,185 | Casey Fossum | Jose Acevedo | Casey Fossum | Phil Norton | Greg Aquino | 509 | 732 | -223 |
| 2004-08-29 | @ CIN | 131 | L 2-6 | 41-90 | 5 | 25,306 | Edgar Gonzalez | Josh Hancock | Todd Van Poppel | Mike Fetters | | 511 | 738 | -227 |
| 2004-08-31 | vs LAN | 132 | L 1-4 | 41-91 | 5 | 39,167 | Randy Johnson | Jeff Weaver | Eric Gagne | Brian Bruney | Giovanni Carrara | 512 | 742 | -230 |
| 2004-09-01 | vs LAN | 133 | W 3-1 | 42-91 | 5 | 34,149 | Brandon Webb | Hideo Nomo | Brandon Webb | Hideo Nomo | Greg Aquino | 515 | 743 | -228 |
| 2004-09-02 | vs LAN | 134 | L 4-8 | 42-92 | 5 | 33,224 | Casey Fossum | Odalis Perez | Yhency Brazoban | Shane Nance | Eric Gagne | 519 | 751 | -232 |
| 2004-09-03 | @ SFN | 135 | L 7-18 | 42-93 | 5 | 38,698 | Edgar Gonzalez | Brad Hennessey | Dave Burba | Edgar Gonzalez | | 526 | 769 | -243 |
| 2004-09-04 | @ SFN | 136 | L 7-9 | 42-94 | 5 | 41,552 | Steve Randolph | Noah Lowry | Scott Eyre | Mike Koplove | Dustin Hermanson | 533 | 778 | -245 |
| 2004-09-05 | @ SFN | 137 | L 1-4 | 42-95 | 5 | 42,099 | Randy Johnson | Brett Tomko | Brett Tomko | Randy Johnson | Dustin Hermanson | 534 | 782 | -248 |
| 2004-09-07 | @ LAN | 138 | L 2-8 | 42-96 | 5 | 35,078 | Brandon Webb | Hideo Nomo | Hideo Nomo | Brandon Webb | | 536 | 790 | -254 |
| 2004-09-08 | @ LAN | 139 | L 5-6 | 42-97 | 5 | 28,888 | Casey Fossum | Odalis Perez | Eric Gagne | Mike Koplove | | 541 | 796 | -255 |
| 2004-09-09 | @ LAN | 140 | L 3-5 | 42-98 | 5 | 27,287 | Edgar Gonzalez | Jose Lima | Jose Lima | Edgar Gonzalez | Eric Gagne | 544 | 801 | -257 |
| 2004-09-10 | vs SFN | 141 | W 2-1 | 43-98 | 5 | 34,284 | Randy Johnson | Brett Tomko | Randy Johnson | Jim Brower | Greg Aquino | 546 | 802 | -256 |
| 2004-09-11 | vs SFN | 142 | L 3-5 | 43-99 | 5 | 36,887 | Steve Randolph | Noah Lowry | Noah Lowry | Steve Randolph | Dustin Hermanson | 549 | 807 | -258 |
| 2004-09-12 | vs SFN | 143 | L 2-5 | 43-100 | 5 | 30,903 | Brandon Webb | Jason Schmidt | Jason Schmidt | Randy Choate | | 551 | 812 | -261 |
| 2004-09-13 | vs COL | 144 | L 2-9 | 43-101 | 5 | 22,070 | Casey Fossum | Joe Kennedy | Joe Kennedy | Casey Fossum | | 553 | 821 | -268 |
| 2004-09-14 | vs COL | 145 | W 4-3 | 44-101 | 5 | 23,175 | Mike Gosling | Jason Jennings | Randy Choate | Steve Reed | | 557 | 824 | -267 |
| 2004-09-15 | vs COL | 146 | W 3-2 | 45-101 | 5 | 22,598 | Randy Johnson | Shawn Estes | Randy Johnson | Shawn Estes | Greg Aquino | 560 | 826 | -266 |
| 2004-09-16 | vs COL | 147 | W 8-5 | 46-101 | 5 | 22,281 | Steve Randolph | Jeff Francis | Chad Durbin | Scott Dohmann | Mike Fetters | 568 | 831 | -263 |
| 2004-09-17 | @ SLN | 148 | L 3-4 | 46-102 | 5 | 37,280 | Brandon Webb | Woody Williams | Jason Isringhausen | Scott Service | | 571 | 835 | -264 |
| 2004-09-18 | @ SLN | 149 | L 0-7 | 46-103 | 5 | 43,791 | Casey Fossum | Chris Carpenter | Dan Haren | Casey Fossum | | 571 | 842 | -271 |
| 2004-09-19 | @ SLN | 150 | W 3-2 | 47-103 | 5 | 41,279 | Mike Gosling | Jeff Suppan | Mike Gosling | Jeff Suppan | Greg Aquino | 574 | 844 | -270 |
| 2004-09-22 | @ COL | 151 | L 2-4 | 47-104 | 5 | 20,125 | Randy Johnson | Shawn Estes | Shawn Estes | Randy Johnson | Shawn Chacon | 576 | 848 | -272 |
| 2004-09-23 | @ COL | 152 | L 1-7 | 47-106 | 5 | 0 | Brandon Webb | Jeff Francis | Jeff Francis | Brandon Webb | | 577 | 855 | -278 |
| 2004-09-23 | @ COL | 153 | L 1-2 | 47-106 | 5 | 20,765 | Casey Fossum | Jamey Wright | Allan Simpson | Randy Choate | | 578 | 857 | -279 |
| 2004-09-24 | @ SDN | 154 | L 5-6 | 47-107 | 5 | 36,927 | Mike Gosling | David Wells | Akinori Otsuka | Greg Aquino | | 583 | 863 | -280 |
| 2004-09-25 | @ SDN | 155 | L 5-6 | 47-108 | 5 | 44,863 | Steve Randolph | Adam Eaton | Antonio Osuna | Chad Durbin | Trevor Hoffman | 588 | 869 | -281 |
| 2004-09-26 | @ SDN | 156 | L 1-7 | 47-109 | 5 | 39,639 | Steve Sparks | Jake Peavy | Jake Peavy | Steve Sparks | | 589 | 876 | -287 |
| 2004-09-27 | vs MIL | 157 | W 3-1 | 48-109 | 5 | 25,123 | Randy Johnson | Ben Sheets | Randy Johnson | Ben Sheets | Greg Aquino | 592 | 877 | -285 |
| 2004-09-28 | vs MIL | 158 | W 9-8 | 49-109 | 5 | 23,936 | Brandon Webb | Jorge de la Rosa | Mike Koplove | Brooks Kieschnick | | 601 | 885 | -284 |
| 2004-09-29 | vs MIL | 159 | L 1-4 | 49-110 | 5 | 21,710 | Casey Fossum | Gary Glover | Gary Glover | Casey Fossum | Luis Vizcaino | 602 | 889 | -287 |
| 2004-10-01 | vs SDN | 160 | L 2-3 | 49-111 | 5 | 25,929 | Mike Gosling | Jake Peavy | Jake Peavy | Mike Gosling | Trevor Hoffman | 604 | 892 | -288 |
| 2004-10-02 | vs SDN | 161 | W 7-6 | 50-111 | 5 | 30,733 | Randy Johnson | Brian Sweeney | Randy Johnson | Mike Bynum | Greg Aquino | 611 | 898 | -287 |
| 2004-10-03 | vs SDN | 162 | W 4-1 | 51-111 | 5 | 29,425 | Brandon Webb | David Wells | Brandon Webb | David Wells | Greg Aquino | 615 | 899 | -284 |