| 1998-04-01 | @ TOR | 1 | L 2-3 | 0-1 | 5 | 41,387 | Bob Tewksbury | Roger Clemens | Roger Clemens | Bob Tewksbury | Randy Myers | 2 | 3 | -1 |
| 1998-04-02 | @ TOR | 2 | W 3-2 | 1-1 | 3 | 25,584 | LaTroy Hawkins | Pat Hentgen | Eddie Guardado | Kelvim Escobar | Rick Aguilera | 5 | 5 | 0 |
| 1998-04-03 | vs KCA | 3 | L 5-9 | 1-2 | 4 | 43,848 | Brad Radke | Chris Haney | Chris Haney | Brad Radke | | 10 | 14 | -4 |
| 1998-04-04 | vs KCA | 4 | L 2-3 | 1-3 | 4 | 18,589 | Mike Morgan | Hipolito Pichardo | Brian Bevil | Eddie Guardado | Jeff Montgomery | 12 | 17 | -5 |
| 1998-04-05 | vs KCA | 5 | W 10-1 | 2-3 | 4 | 10,851 | Eric Milton | Tim Belcher | Eric Milton | Tim Belcher | | 22 | 18 | 4 |
| 1998-04-07 | vs TOR | 6 | W 12-2 | 3-3 | 3 | 8,421 | Bob Tewksbury | Roger Clemens | Bob Tewksbury | Roger Clemens | | 34 | 20 | 14 |
| 1998-04-08 | vs TOR | 7 | L 6-9 | 3-4 | 4 | 8,532 | LaTroy Hawkins | Pat Hentgen | Pat Hentgen | LaTroy Hawkins | Randy Myers | 40 | 29 | 11 |
| 1998-04-09 | vs TOR | 8 | W 13-2 | 4-4 | 2 | 9,075 | Brad Radke | Juan Guzman | Brad Radke | Juan Guzman | | 53 | 31 | 22 |
| 1998-04-10 | @ KCA | 9 | L 4-5 | 4-5 | 4 | 14,341 | Mike Morgan | Chris Haney | Brian Bevil | Rick Aguilera | | 57 | 36 | 21 |
| 1998-04-11 | @ KCA | 10 | W 8-3 | 5-5 | 2 | 18,087 | Eric Milton | Tim Belcher | Eric Milton | Tim Belcher | | 65 | 39 | 26 |
| 1998-04-12 | @ KCA | 11 | W 7-2 | 6-5 | 2 | 11,875 | Bob Tewksbury | Hipolito Pichardo | Bob Tewksbury | Hipolito Pichardo | Rick Aguilera | 72 | 41 | 31 |
| 1998-04-13 | @ TBA | 12 | L 12-13 | 6-6 | 2 | 31,969 | LaTroy Hawkins | Rolando Arrojo | Esteban Yan | Mike Trombley | | 84 | 54 | 30 |
| 1998-04-14 | @ TBA | 13 | W 8-2 | 7-6 | 2 | 34,337 | Brad Radke | Dennis Springer | Brad Radke | Dennis Springer | | 92 | 56 | 36 |
| 1998-04-16 | vs SEA | 14 | L 2-3 | 7-7 | 2 | 11,351 | Mike Morgan | Jamie Moyer | Mike Timlin | Rick Aguilera | Bobby Ayala | 94 | 59 | 35 |
| 1998-04-17 | vs SEA | 15 | L 6-11 | 7-8 | 2 | 18,169 | Eric Milton | Jeff Fassero | Jeff Fassero | Eric Milton | | 100 | 70 | 30 |
| 1998-04-18 | vs SEA | 16 | L 3-5 | 7-9 | 2 | 23,943 | Bob Tewksbury | Ken Cloude | Ken Cloude | Bob Tewksbury | Bobby Ayala | 103 | 75 | 28 |
| 1998-04-19 | vs SEA | 17 | L 4-7 | 7-10 | 3 | 15,124 | LaTroy Hawkins | Bill Swift | Bill Swift | LaTroy Hawkins | Mike Timlin | 107 | 82 | 25 |
| 1998-04-20 | @ OAK | 18 | L 2-3 | 7-11 | 3 | 5,000 | Brad Radke | Jimmy Haynes | Buddy Groom | Greg Swindell | Billy Taylor | 109 | 85 | 24 |
| 1998-04-21 | @ OAK | 19 | L 4-5 | 7-12 | 3 | 5,829 | Mike Morgan | Tom Candiotti | T.J. Mathews | Hector Carrasco | | 113 | 90 | 23 |
| 1998-04-22 | @ OAK | 20 | W 4-2 | 8-12 | 3 | 7,491 | Eric Milton | Mike Oquist | Eddie Guardado | T.J. Mathews | Rick Aguilera | 117 | 92 | 25 |
| 1998-04-24 | @ SEA | 21 | L 2-4 | 8-13 | 3 | 28,157 | Bob Tewksbury | Ken Cloude | Ken Cloude | Bob Tewksbury | Bobby Ayala | 119 | 96 | 23 |
| 1998-04-25 | @ SEA | 22 | W 8-2 | 9-13 | 3 | 51,880 | LaTroy Hawkins | Bill Swift | Rick Aguilera | Mike Timlin | | 127 | 98 | 29 |
| 1998-04-26 | @ SEA | 23 | W 2-0 | 10-13 | 2 | 31,732 | Brad Radke | Jamie Moyer | Brad Radke | Jamie Moyer | Rick Aguilera | 129 | 98 | 31 |
| 1998-04-27 | vs TEX | 24 | L 4-9 | 10-14 | 4 | 8,349 | Mike Morgan | Rick Helling | Rick Helling | Mike Morgan | | 133 | 107 | 26 |
| 1998-04-28 | vs TEX | 25 | L 2-7 | 10-15 | 4 | 8,570 | Eric Milton | Darren Oliver | Darren Oliver | Eric Milton | | 135 | 114 | 21 |
| 1998-04-29 | vs TBA | 26 | W 2-0 | 11-15 | 4 | 8,964 | Bob Tewksbury | Wilson Alvarez | Bob Tewksbury | Wilson Alvarez | Rick Aguilera | 137 | 114 | 23 |
| 1998-04-30 | vs TBA | 27 | L 0-2 | 11-16 | 4 | 8,860 | LaTroy Hawkins | Rolando Arrojo | Rolando Arrojo | LaTroy Hawkins | | 137 | 116 | 21 |
| 1998-05-01 | @ BAL | 28 | L 3-6 | 11-17 | 4 | 43,233 | Brad Radke | Doug Drabek | Doug Drabek | Brad Radke | Armando Benitez | 140 | 122 | 18 |
| 1998-05-02 | @ BAL | 29 | W 8-7 | 12-17 | 3 | 45,237 | Mike Morgan | Scott Erickson | Rick Aguilera | Doug Johns | | 148 | 129 | 19 |
| 1998-05-03 | @ BAL | 30 | L 0-2 | 12-18 | 4 | 43,930 | Eric Milton | Mike Mussina | Mike Mussina | Eric Milton | Arthur Rhodes | 148 | 131 | 17 |
| 1998-05-05 | @ BOS | 31 | L 2-4 | 12-19 | 4 | 20,882 | Bob Tewksbury | Tim Wakefield | Tim Wakefield | Bob Tewksbury | Tom Gordon | 150 | 135 | 15 |
| 1998-05-06 | @ BOS | 32 | W 8-7 | 13-19 | 4 | 20,954 | LaTroy Hawkins | Robinson Checo | LaTroy Hawkins | Robinson Checo | | 158 | 142 | 16 |
| 1998-05-08 | vs NYA | 33 | L 1-5 | 13-20 | 4 | 22,612 | Brad Radke | Hideki Irabu | Hideki Irabu | Brad Radke | Jeff Nelson | 159 | 147 | 12 |
| 1998-05-09 | vs NYA | 34 | W 8-1 | 14-20 | 3 | 20,471 | Mike Morgan | Andy Pettitte | Mike Morgan | Andy Pettitte | | 167 | 148 | 19 |
| 1998-05-10 | vs NYA | 35 | L 0-7 | 14-21 | 3 | 12,444 | Eric Milton | Ramiro Mendoza | Ramiro Mendoza | Eric Milton | | 167 | 155 | 12 |
| 1998-05-11 | vs BAL | 36 | L 0-4 | 14-22 | 4 | 9,317 | Bob Tewksbury | Scott Erickson | Scott Erickson | Bob Tewksbury | | 167 | 159 | 8 |
| 1998-05-12 | vs BAL | 37 | W 7-4 | 15-22 | 3 | 8,666 | LaTroy Hawkins | Scott Kamieniecki | LaTroy Hawkins | Arthur Rhodes | Rick Aguilera | 174 | 163 | 11 |
| 1998-05-13 | vs BOS | 38 | W 7-4 | 16-22 | 3 | 9,076 | Brad Radke | Bret Saberhagen | Brad Radke | Bret Saberhagen | Rick Aguilera | 181 | 167 | 14 |
| 1998-05-14 | vs BOS | 39 | W 2-1 | 17-22 | 3 | 12,121 | Mike Morgan | Pedro Martinez | Mike Trombley | John Wasdin | | 183 | 168 | 15 |
| 1998-05-15 | @ NYA | 40 | W 7-6 | 18-22 | 3 | 31,272 | Eric Milton | Andy Pettitte | Eric Milton | Andy Pettitte | Rick Aguilera | 190 | 174 | 16 |
| 1998-05-16 | @ NYA | 41 | L 2-5 | 18-23 | 3 | 35,137 | Bob Tewksbury | Ramiro Mendoza | Ramiro Mendoza | Bob Tewksbury | Mariano Rivera | 192 | 179 | 13 |
| 1998-05-17 | @ NYA | 42 | L 0-4 | 18-24 | 3 | 49,820 | LaTroy Hawkins | David Wells | David Wells | LaTroy Hawkins | | 192 | 183 | 9 |
| 1998-05-19 | vs DET | 43 | W 8-3 | 19-24 | 3 | 11,799 | Brad Radke | A.J. Sager | Brad Radke | A.J. Sager | | 200 | 186 | 14 |
| 1998-05-20 | vs DET | 44 | L 11-12 | 19-25 | 3 | 9,442 | Mike Morgan | Frank Castillo | Sean Runyan | Dan Naulty | Todd Jones | 211 | 198 | 13 |
| 1998-05-21 | vs DET | 45 | L 3-6 | 19-26 | 3 | 12,347 | Eric Milton | Tim Worrell | Doug Brocail | Mike Trombley | Todd Jones | 214 | 204 | 10 |
| 1998-05-22 | @ ANA | 46 | L 3-10 | 19-27 | 4 | 34,363 | Bob Tewksbury | Omar Olivares | Omar Olivares | Bob Tewksbury | | 217 | 214 | 3 |
| 1998-05-23 | @ ANA | 47 | W 9-5 | 20-27 | 3 | 31,036 | LaTroy Hawkins | Allen Watson | LaTroy Hawkins | Allen Watson | Greg Swindell | 226 | 219 | 7 |
| 1998-05-24 | @ ANA | 48 | W 9-1 | 21-27 | 2 | 24,728 | Brad Radke | Chuck Finley | Brad Radke | Chuck Finley | | 235 | 220 | 15 |
| 1998-05-25 | @ TEX | 49 | W 9-3 | 22-27 | 2 | 30,887 | Mike Morgan | Darren Oliver | Mike Morgan | Darren Oliver | | 244 | 223 | 21 |
| 1998-05-27 | @ TEX | 50 | W 6-5 | 23-27 | 2 | 32,657 | Eric Milton | John Burkett | Mike Trombley | Xavier Hernandez | Rick Aguilera | 250 | 228 | 22 |
| 1998-05-29 | vs ANA | 51 | L 1-3 | 23-28 | 2 | 14,633 | LaTroy Hawkins | Chuck Finley | Chuck Finley | LaTroy Hawkins | Troy Percival | 251 | 231 | 20 |
| 1998-05-30 | vs ANA | 52 | W 8-1 | 24-28 | 2 | 16,827 | Brad Radke | Ken Hill | Brad Radke | Ken Hill | | 259 | 232 | 27 |
| 1998-05-31 | vs ANA | 53 | L 5-6 | 24-29 | 2 | 11,285 | Mike Morgan | Jack McDowell | Jason Dickson | Greg Swindell | Troy Percival | 264 | 238 | 26 |
| 1998-06-01 | vs OAK | 54 | L 5-8 | 24-30 | 2 | 7,918 | Eric Milton | Mike Oquist | Mike Oquist | Eric Milton | Billy Taylor | 269 | 246 | 23 |
| 1998-06-02 | vs OAK | 55 | W 10-3 | 25-30 | 2 | 10,820 | Dan Serafini | Tom Candiotti | Dan Serafini | Tom Candiotti | | 279 | 249 | 30 |
| 1998-06-03 | vs CLE | 56 | W 3-2 | 26-30 | 2 | 8,897 | LaTroy Hawkins | Bartolo Colon | Greg Swindell | Bartolo Colon | Rick Aguilera | 282 | 251 | 31 |
| 1998-06-04 | vs CLE | 57 | L 2-3 | 26-31 | 2 | 9,417 | Brad Radke | Dwight Gooden | Dwight Gooden | Brad Radke | Michael Jackson | 284 | 254 | 30 |
| 1998-06-05 | @ PIT | 58 | L 1-6 | 26-32 | 2 | 28,446 | Mike Morgan | Jose Silva | Jose Silva | Mike Morgan | | 285 | 260 | 25 |
| 1998-06-06 | @ PIT | 59 | L 3-4 | 26-33 | 2 | 19,809 | Eric Milton | Francisco Cordova | Esteban Loaiza | Rick Aguilera | | 288 | 264 | 24 |
| 1998-06-07 | @ PIT | 60 | W 3-2 | 27-33 | 2 | 32,773 | Bob Tewksbury | Jason Schmidt | Dan Serafini | Jason Schmidt | Rick Aguilera | 291 | 266 | 25 |
| 1998-06-08 | vs CHN | 61 | L 1-8 | 27-34 | 2 | 18,077 | LaTroy Hawkins | Mark Clark | Mark Clark | LaTroy Hawkins | | 292 | 274 | 18 |
| 1998-06-09 | vs CHN | 62 | W 8-0 | 28-34 | 2 | 25,806 | Brad Radke | Kerry Wood | Brad Radke | Kerry Wood | | 300 | 274 | 26 |
| 1998-06-10 | vs CHN | 63 | W 5-1 | 29-34 | 2 | 15,086 | Mike Morgan | Steve Trachsel | Mike Morgan | Steve Trachsel | Rick Aguilera | 305 | 275 | 30 |
| 1998-06-12 | vs CHA | 64 | W 8-7 | 30-34 | 2 | 10,520 | Eric Milton | Scott Eyre | Rick Aguilera | Bill Simas | | 313 | 282 | 31 |
| 1998-06-13 | vs CHA | 65 | L 2-3 | 30-35 | 2 | 16,593 | Bob Tewksbury | Mike Sirotka | Mike Sirotka | Bob Tewksbury | Matt Karchner | 315 | 285 | 30 |
| 1998-06-14 | vs CHA | 66 | W 2-1 | 31-35 | 2 | 14,945 | LaTroy Hawkins | Jaime Navarro | LaTroy Hawkins | Jaime Navarro | Rick Aguilera | 317 | 286 | 31 |
| 1998-06-15 | @ DET | 67 | L 2-3 | 31-36 | 2 | 11,326 | Brad Radke | Brian Moehler | Brian Moehler | Brad Radke | Todd Jones | 319 | 289 | 30 |
| 1998-06-16 | @ DET | 68 | W 8-5 | 32-36 | 2 | 8,493 | Mike Morgan | Denny Harriger | Dan Serafini | Denny Harriger | Rick Aguilera | 327 | 294 | 33 |
| 1998-06-17 | @ DET | 69 | L 2-6 | 32-37 | 2 | 10,152 | Eric Milton | Bryce Florie | Bryce Florie | Eric Milton | | 329 | 300 | 29 |
| 1998-06-18 | @ CHA | 70 | W 4-1 | 33-37 | 2 | 13,550 | Bob Tewksbury | Mike Sirotka | Bob Tewksbury | Mike Sirotka | | 333 | 301 | 32 |
| 1998-06-19 | @ CHA | 71 | W 10-6 | 34-37 | 2 | 18,905 | LaTroy Hawkins | Jaime Navarro | Mike Trombley | Jaime Navarro | Greg Swindell | 343 | 307 | 36 |
| 1998-06-20 | @ CHA | 72 | L 7-8 | 34-38 | 2 | 19,823 | Brad Radke | James Baldwin | Bill Simas | Rick Aguilera | | 350 | 315 | 35 |
| 1998-06-21 | @ CHA | 73 | W 6-1 | 35-38 | 2 | 15,926 | Mike Morgan | Jason Bere | Mike Morgan | Jason Bere | Hector Carrasco | 356 | 316 | 40 |
| 1998-06-22 | @ HOU | 74 | W 5-3 | 36-38 | 2 | 23,168 | Eric Milton | Jose Lima | Eric Milton | Jose Lima | Rick Aguilera | 361 | 319 | 42 |
| 1998-06-23 | @ HOU | 75 | L 0-9 | 36-39 | 2 | 27,157 | Bob Tewksbury | Shane Reynolds | Shane Reynolds | Bob Tewksbury | | 361 | 328 | 33 |
| 1998-06-24 | vs MIL | 76 | L 1-3 | 36-40 | 2 | 12,860 | LaTroy Hawkins | Steve Woodard | Steve Woodard | LaTroy Hawkins | Bob Wickman | 362 | 331 | 31 |
| 1998-06-25 | vs MIL | 77 | L 2-9 | 36-41 | 2 | 16,286 | Brad Radke | Cal Eldred | Cal Eldred | Brad Radke | | 364 | 340 | 24 |
| 1998-06-26 | vs SLN | 78 | W 5-1 | 37-41 | 2 | 29,089 | Mike Morgan | Juan Acevedo | Greg Swindell | Juan Acevedo | | 369 | 341 | 28 |
| 1998-06-27 | vs SLN | 79 | L 2-7 | 37-42 | 2 | 35,002 | Eric Milton | Todd Stottlemyre | Todd Stottlemyre | Eric Milton | | 371 | 348 | 23 |
| 1998-06-28 | vs SLN | 80 | W 3-2 | 38-42 | 2 | 29,110 | Bob Tewksbury | Kent Bottenfield | Hector Carrasco | Kent Bottenfield | Rick Aguilera | 374 | 350 | 24 |
| 1998-06-30 | @ CIN | 81 | L 3-6 | 38-43 | 2 | 19,315 | LaTroy Hawkins | Brett Tomko | Brett Tomko | LaTroy Hawkins | Jeff Shaw | 377 | 356 | 21 |
| 1998-07-01 | @ CIN | 82 | W 2-1 | 39-43 | 2 | 15,592 | Brad Radke | Scott Winchester | Brad Radke | Scott Sullivan | Rick Aguilera | 379 | 357 | 22 |
| 1998-07-02 | @ CIN | 83 | L 7-8 | 39-44 | 2 | 16,528 | Eric Milton | Pete Harnisch | Jeff Shaw | Rick Aguilera | | 386 | 365 | 21 |
| 1998-07-03 | vs DET | 84 | L 4-5 | 39-45 | 2 | 10,818 | Bob Tewksbury | Frank Castillo | Doug Brocail | Dan Naulty | Todd Jones | 390 | 370 | 20 |
| 1998-07-04 | vs DET | 85 | L 2-4 | 39-46 | 2 | 14,067 | Dan Serafini | Justin Thompson | Justin Thompson | Dan Serafini | Todd Jones | 392 | 374 | 18 |
| 1998-07-05 | vs DET | 86 | W 5-4 | 40-46 | 2 | 10,060 | LaTroy Hawkins | Brian Moehler | LaTroy Hawkins | Brian Moehler | Rick Aguilera | 397 | 378 | 19 |
| 1998-07-09 | @ CLE | 87 | W 3-0 | 41-46 | 2 | 43,236 | Bob Tewksbury | Dave Burba | Bob Tewksbury | Dave Burba | Rick Aguilera | 400 | 378 | 22 |
| 1998-07-10 | @ CLE | 88 | L 5-6 | 41-47 | 2 | 43,182 | LaTroy Hawkins | Bartolo Colon | Michael Jackson | Mike Trombley | | 405 | 384 | 21 |
| 1998-07-11 | @ CLE | 89 | L 2-12 | 41-48 | 2 | 43,140 | Brad Radke | Dwight Gooden | Dwight Gooden | Brad Radke | | 407 | 396 | 11 |
| 1998-07-12 | @ CLE | 90 | W 11-6 | 42-48 | 2 | 43,053 | Eric Milton | Charles Nagy | Eric Milton | Charles Nagy | | 418 | 402 | 16 |
| 1998-07-13 | @ CHA | 91 | L 2-5 | 42-49 | 2 | 16,741 | Dan Serafini | John Snyder | John Snyder | Dan Serafini | Bill Simas | 420 | 407 | 13 |
| 1998-07-14 | @ CHA | 92 | L 5-8 | 42-50 | 2 | 13,841 | Bob Tewksbury | Mike Sirotka | Keith Foulke | Rick Aguilera | | 425 | 415 | 10 |
| 1998-07-15 | @ SEA | 93 | L 1-4 | 42-51 | 3 | 23,250 | LaTroy Hawkins | Jamie Moyer | Jamie Moyer | LaTroy Hawkins | Mike Timlin | 426 | 419 | 7 |
| 1998-07-16 | @ SEA | 94 | L 0-3 | 42-52 | 3 | 24,974 | Brad Radke | Randy Johnson | Randy Johnson | Brad Radke | | 426 | 422 | 4 |
| 1998-07-17 | @ OAK | 95 | W 8-7 | 43-52 | 2 | 10,682 | Eric Milton | Jimmy Haynes | Hector Carrasco | Billy Taylor | Rick Aguilera | 434 | 429 | 5 |
| 1998-07-18 | @ OAK | 96 | W 4-3 | 44-52 | 2 | 16,711 | Mike Trombley | Mike Oquist | Hector Carrasco | Mike Oquist | Rick Aguilera | 438 | 432 | 6 |
| 1998-07-19 | @ OAK | 97 | L 2-5 | 44-53 | 2 | 15,117 | Dan Serafini | Kenny Rogers | Kenny Rogers | Dan Serafini | | 440 | 437 | 3 |
| 1998-07-21 | vs ANA | 98 | W 4-2 | 45-53 | 2 | 11,869 | LaTroy Hawkins | Allen Watson | LaTroy Hawkins | Allen Watson | Rick Aguilera | 444 | 439 | 5 |
| 1998-07-22 | vs ANA | 99 | L 3-5 | 45-54 | 2 | 10,484 | Brad Radke | Steve Sparks | Shigetoshi Hasegawa | Greg Swindell | Troy Percival | 447 | 444 | 3 |
| 1998-07-23 | vs ANA | 100 | L 5-6 | 45-55 | 2 | 18,059 | Eric Milton | Jason Dickson | Pep Harris | Hector Carrasco | Troy Percival | 452 | 450 | 2 |
| 1998-07-24 | vs TEX | 101 | W 5-3 | 46-55 | 2 | 11,473 | Dan Serafini | Esteban Loaiza | Dan Serafini | Esteban Loaiza | Rick Aguilera | 457 | 453 | 4 |
| 1998-07-25 | vs TEX | 102 | W 7-6 | 47-55 | 2 | 21,013 | Frankie Rodriguez | John Burkett | Greg Swindell | Danny Patterson | Rick Aguilera | 464 | 459 | 5 |
| 1998-07-26 | vs TEX | 103 | W 11-3 | 48-55 | 2 | 13,802 | LaTroy Hawkins | Rick Helling | LaTroy Hawkins | Rick Helling | | 475 | 462 | 13 |
| 1998-07-28 | @ KCA | 104 | W 3-0 | 49-55 | 2 | 14,365 | Brad Radke | Glendon Rusch | Brad Radke | Glendon Rusch | Rick Aguilera | 478 | 462 | 16 |
| 1998-07-29 | @ KCA | 105 | W 5-3 | 50-55 | 2 | 14,362 | Eric Milton | Hipolito Pichardo | Eric Milton | Hipolito Pichardo | Rick Aguilera | 483 | 465 | 18 |
| 1998-07-30 | @ KCA | 106 | L 3-7 | 50-56 | 2 | 20,466 | Dan Serafini | Tim Belcher | Tim Belcher | Dan Serafini | | 486 | 472 | 14 |
| 1998-07-31 | vs TOR | 107 | W 6-4 | 51-56 | 2 | 26,054 | Frankie Rodriguez | Woody Williams | Frankie Rodriguez | Woody Williams | Rick Aguilera | 492 | 476 | 16 |
| 1998-08-01 | vs TOR | 108 | L 9-10 | 51-57 | 2 | 17,128 | LaTroy Hawkins | Pat Hentgen | Pat Hentgen | LaTroy Hawkins | Randy Myers | 501 | 486 | 15 |
| 1998-08-02 | vs TOR | 109 | L 4-6 | 51-58 | 2 | 40,096 | Brad Radke | Roger Clemens | Roger Clemens | Brad Radke | Randy Myers | 505 | 492 | 13 |
| 1998-08-04 | vs KCA | 110 | L 4-12 | 51-59 | 2 | 11,014 | Eric Milton | Hipolito Pichardo | Hipolito Pichardo | Eric Milton | | 509 | 504 | 5 |
| 1998-08-05 | vs KCA | 111 | L 3-4 | 51-60 | 2 | 9,545 | Frankie Rodriguez | Tim Belcher | Tim Belcher | Frankie Rodriguez | Jeff Montgomery | 512 | 508 | 4 |
| 1998-08-06 | vs KCA | 112 | L 7-8 | 51-61 | 3 | 14,332 | Dan Serafini | Jose Rosado | Scott Service | Rick Aguilera | Jeff Montgomery | 519 | 516 | 3 |
| 1998-08-07 | vs BAL | 113 | L 9-16 | 51-62 | 3 | 13,662 | LaTroy Hawkins | Scott Erickson | Jimmy Key | Travis Miller | | 528 | 532 | -4 |
| 1998-08-08 | vs BAL | 114 | L 3-6 | 51-63 | 4 | 18,396 | Brad Radke | Sidney Ponson | Sidney Ponson | Brad Radke | Jesse Orosco | 531 | 538 | -7 |
| 1998-08-09 | vs BAL | 115 | W 5-4 | 52-63 | 2 | 16,780 | Dan Serafini | Mike Mussina | Dan Serafini | Mike Mussina | Rick Aguilera | 536 | 542 | -6 |
| 1998-08-10 | @ NYA | 116 | L 3-7 | 52-64 | 3 | 29,600 | Frankie Rodriguez | Hideki Irabu | Hideki Irabu | Frankie Rodriguez | | 539 | 549 | -10 |
| 1998-08-11 | @ NYA | 117 | L 0-7 | 52-65 | 3 | 37,413 | Eric Milton | David Wells | David Wells | Eric Milton | | 539 | 556 | -17 |
| 1998-08-12 | @ NYA | 118 | L 2-11 | 52-66 | 4 | 47,841 | LaTroy Hawkins | David Cone | David Cone | LaTroy Hawkins | | 541 | 567 | -26 |
| 1998-08-13 | @ BOS | 119 | L 7-8 | 52-67 | 4 | 32,801 | Brad Radke | Pedro Martinez | Dennis Eckersley | Travis Miller | Tom Gordon | 548 | 575 | -27 |
| 1998-08-14 | @ BOS | 120 | L 12-13 | 52-68 | 4 | 32,888 | Dan Serafini | Tim Wakefield | Derek Lowe | Travis Baptist | Tom Gordon | 560 | 588 | -28 |
| 1998-08-15 | @ BOS | 121 | W 3-2 | 53-68 | 4 | 32,412 | Frankie Rodriguez | John Wasdin | Frankie Rodriguez | Pete Schourek | Rick Aguilera | 563 | 590 | -27 |
| 1998-08-16 | @ BOS | 122 | W 6-3 | 54-68 | 4 | 30,893 | Eric Milton | Steve Avery | Eric Milton | Steve Avery | Rick Aguilera | 569 | 593 | -24 |
| 1998-08-17 | @ BAL | 123 | L 2-3 | 54-69 | 4 | 46,606 | LaTroy Hawkins | Scott Erickson | Scott Erickson | LaTroy Hawkins | Armando Benitez | 571 | 596 | -25 |
| 1998-08-18 | @ BAL | 124 | L 1-7 | 54-70 | 4 | 44,022 | Brad Radke | Sidney Ponson | Sidney Ponson | Brad Radke | | 572 | 603 | -31 |
| 1998-08-19 | vs NYA | 125 | W 5-3 | 55-70 | 3 | 17,923 | Mike Morgan | Andy Pettitte | Dan Serafini | Andy Pettitte | Rick Aguilera | 577 | 606 | -29 |
| 1998-08-20 | vs NYA | 126 | W 9-4 | 56-70 | 3 | 18,548 | Frankie Rodriguez | Mike Buddie | Frankie Rodriguez | Mike Buddie | | 586 | 610 | -24 |
| 1998-08-21 | vs BOS | 127 | L 2-9 | 56-71 | 4 | 16,786 | Eric Milton | Steve Avery | Steve Avery | Eric Milton | | 588 | 619 | -31 |
| 1998-08-22 | vs BOS | 128 | W 4-3 | 57-71 | 4 | 18,415 | LaTroy Hawkins | John Wasdin | Mike Trombley | Greg Swindell | | 592 | 622 | -30 |
| 1998-08-23 | vs BOS | 129 | L 1-5 | 57-72 | 4 | 12,686 | Brad Radke | Pedro Martinez | Pedro Martinez | Brad Radke | | 593 | 627 | -34 |
| 1998-08-25 | @ TBA | 130 | W 4-1 | 58-72 | 3 | 23,126 | Frankie Rodriguez | Rolando Arrojo | Frankie Rodriguez | Rolando Arrojo | Rick Aguilera | 597 | 628 | -31 |
| 1998-08-26 | @ TBA | 131 | W 7-3 | 59-72 | 3 | 23,059 | Bob Tewksbury | Tony Saunders | Bob Tewksbury | Tony Saunders | Rick Aguilera | 604 | 631 | -27 |
| 1998-08-27 | @ TBA | 132 | L 3-10 | 59-73 | 4 | 23,314 | Eric Milton | Julio Santana | Julio Santana | Eric Milton | | 607 | 641 | -34 |
| 1998-08-28 | @ TOR | 133 | L 6-7 | 59-74 | 4 | 26,268 | LaTroy Hawkins | Woody Williams | Woody Williams | Mike Trombley | Dan Plesac | 613 | 648 | -35 |
| 1998-08-29 | @ TOR | 134 | L 7-14 | 59-75 | 4 | 30,101 | Brad Radke | Dave Stieb | Dave Stieb | Brad Radke | | 620 | 662 | -42 |
| 1998-08-30 | @ TOR | 135 | L 0-6 | 59-76 | 4 | 29,202 | Frankie Rodriguez | Roger Clemens | Roger Clemens | Frankie Rodriguez | | 620 | 668 | -48 |
| 1998-08-31 | vs TBA | 136 | W 2-1 | 60-76 | 4 | 7,888 | Bob Tewksbury | Tony Saunders | Bob Tewksbury | Tony Saunders | Rick Aguilera | 622 | 669 | -47 |
| 1998-09-01 | vs TBA | 137 | W 6-5 | 61-76 | 4 | 7,947 | Eric Milton | Julio Santana | Dan Serafini | Roberto Hernandez | | 628 | 674 | -46 |
| 1998-09-02 | vs TBA | 138 | L 1-4 | 61-77 | 4 | 7,165 | LaTroy Hawkins | Wilson Alvarez | Esteban Yan | LaTroy Hawkins | Albie Lopez | 629 | 678 | -49 |
| 1998-09-03 | vs TBA | 139 | W 5-4 | 62-77 | 4 | 7,072 | Brad Radke | Bryan Rekar | Eddie Guardado | Rick White | | 634 | 682 | -48 |
| 1998-09-04 | @ TEX | 140 | L 3-9 | 62-78 | 4 | 25,580 | Frankie Rodriguez | Aaron Sele | Aaron Sele | Frankie Rodriguez | | 637 | 691 | -54 |
| 1998-09-05 | @ TEX | 141 | W 7-4 | 63-78 | 4 | 38,581 | Bob Tewksbury | Todd Stottlemyre | Mike Trombley | Xavier Hernandez | Rick Aguilera | 644 | 695 | -51 |
| 1998-09-06 | @ TEX | 142 | W 6-5 | 64-78 | 4 | 35,328 | Eric Milton | Esteban Loaiza | Hector Carrasco | Xavier Hernandez | Rick Aguilera | 650 | 700 | -50 |
| 1998-09-07 | @ TEX | 143 | L 0-6 | 64-79 | 4 | 24,519 | LaTroy Hawkins | Rick Helling | Rick Helling | LaTroy Hawkins | | 650 | 706 | -56 |
| 1998-09-08 | @ ANA | 144 | W 5-0 | 65-79 | 4 | 20,444 | Brad Radke | Steve Sparks | Brad Radke | Steve Sparks | | 655 | 706 | -51 |
| 1998-09-09 | @ ANA | 145 | L 8-10 | 65-80 | 4 | 20,070 | Frankie Rodriguez | Ken Hill | Omar Olivares | Frankie Rodriguez | Troy Percival | 663 | 716 | -53 |
| 1998-09-11 | vs OAK | 146 | L 2-3 | 65-81 | 4 | 9,333 | Bob Tewksbury | Kenny Rogers | Kenny Rogers | Bob Tewksbury | | 665 | 719 | -54 |
| 1998-09-12 | vs OAK | 147 | L 5-6 | 65-82 | 4 | 11,771 | Eric Milton | Tom Candiotti | Jay Witasick | Eric Milton | Billy Taylor | 670 | 725 | -55 |
| 1998-09-13 | vs OAK | 148 | L 6-9 | 65-83 | 4 | 8,454 | LaTroy Hawkins | Mike Oquist | Mark Holzemer | Rick Aguilera | Billy Taylor | 676 | 734 | -58 |
| 1998-09-14 | vs SEA | 149 | L 3-10 | 65-84 | 4 | 9,711 | Brad Radke | Mac Suzuki | Mac Suzuki | Brad Radke | | 679 | 744 | -65 |
| 1998-09-15 | vs SEA | 150 | L 7-12 | 65-85 | 4 | 8,024 | Frankie Rodriguez | Paul Abbott | Paul Abbott | Frankie Rodriguez | | 686 | 756 | -70 |
| 1998-09-16 | @ CLE | 151 | L 6-8 | 65-86 | 4 | 43,277 | Bob Tewksbury | Charles Nagy | Charles Nagy | Bob Tewksbury | Paul Assenmacher | 692 | 764 | -72 |
| 1998-09-17 | @ CLE | 152 | L 1-9 | 65-87 | 4 | 43,299 | Eric Milton | Dave Burba | Dave Burba | Eric Milton | | 693 | 773 | -80 |
| 1998-09-18 | @ DET | 153 | L 4-5 | 65-88 | 4 | 13,661 | LaTroy Hawkins | Brian Moehler | Matt Anderson | Mike Trombley | | 697 | 778 | -81 |
| 1998-09-19 | @ DET | 154 | L 7-8 | 65-89 | 4 | 15,536 | Brad Radke | Frank Castillo | A.J. Sager | Rick Aguilera | | 704 | 786 | -82 |
| 1998-09-20 | @ DET | 155 | W 3-0 | 66-89 | 4 | 19,092 | Benj Sampson | Seth Greisinger | Benj Sampson | Seth Greisinger | Rick Aguilera | 707 | 786 | -79 |
| 1998-09-21 | vs CHA | 156 | L 1-7 | 66-90 | 4 | 6,862 | Bob Tewksbury | Jim Abbott | Jim Abbott | Bob Tewksbury | | 708 | 793 | -85 |
| 1998-09-22 | vs CHA | 157 | L 1-4 | 66-91 | 4 | 7,313 | Eric Milton | James Baldwin | James Baldwin | Eric Milton | | 709 | 797 | -88 |
| 1998-09-23 | vs CHA | 158 | W 7-6 | 67-91 | 4 | 6,765 | LaTroy Hawkins | Jim Parque | Mike Trombley | Scott Eyre | | 716 | 803 | -87 |
| 1998-09-24 | vs CLE | 159 | W 2-0 | 68-91 | 4 | 7,800 | Brad Radke | Jaret Wright | Brad Radke | Jaret Wright | Rick Aguilera | 718 | 803 | -85 |
| 1998-09-25 | vs CLE | 160 | W 5-4 | 69-91 | 4 | 11,940 | Benj Sampson | Dwight Gooden | Rick Aguilera | Paul Shuey | | 723 | 807 | -84 |
| 1998-09-26 | vs CLE | 161 | L 5-9 | 69-92 | 4 | 28,764 | Bob Tewksbury | Charles Nagy | Dave Burba | Bob Tewksbury | | 728 | 816 | -88 |
| 1998-09-27 | vs CLE | 162 | W 6-2 | 70-92 | 4 | 12,049 | Eric Milton | Bartolo Colon | Eric Milton | Bartolo Colon | Mike Trombley | 734 | 818 | -84 |