| 1998-04-01 | vs MIN | 1 | W 3-2 | 1-0 | 2 | 41,387 | Roger Clemens | Bob Tewksbury | Roger Clemens | Bob Tewksbury | Randy Myers | 3 | 2 | 1 |
| 1998-04-02 | vs MIN | 2 | L 2-3 | 1-1 | 4 | 25,584 | Pat Hentgen | LaTroy Hawkins | Eddie Guardado | Kelvim Escobar | Rick Aguilera | 5 | 5 | 0 |
| 1998-04-03 | vs TEX | 3 | L 0-5 | 1-2 | 4 | 25,509 | Juan Guzman | Rick Helling | Rick Helling | Juan Guzman | | 5 | 10 | -5 |
| 1998-04-04 | vs TEX | 4 | W 9-2 | 2-2 | 4 | 30,156 | Woody Williams | Darren Oliver | Woody Williams | Darren Oliver | | 14 | 12 | 2 |
| 1998-04-05 | vs TEX | 5 | L 5-6 | 2-3 | 4 | 28,106 | Chris Carpenter | John Burkett | John Burkett | Bill Risley | John Wetteland | 19 | 18 | 1 |
| 1998-04-07 | @ MIN | 6 | L 2-12 | 2-4 | 5 | 8,421 | Roger Clemens | Bob Tewksbury | Bob Tewksbury | Roger Clemens | | 21 | 30 | -9 |
| 1998-04-08 | @ MIN | 7 | W 9-6 | 3-4 | 4 | 8,532 | Pat Hentgen | LaTroy Hawkins | Pat Hentgen | LaTroy Hawkins | Randy Myers | 30 | 36 | -6 |
| 1998-04-09 | @ MIN | 8 | L 2-13 | 3-5 | 5 | 9,075 | Juan Guzman | Brad Radke | Brad Radke | Juan Guzman | | 32 | 49 | -17 |
| 1998-04-10 | @ TEX | 9 | L 3-4 | 3-6 | 5 | 32,314 | Woody Williams | Rick Helling | Rick Helling | Dan Plesac | John Wetteland | 35 | 53 | -18 |
| 1998-04-11 | @ TEX | 10 | W 9-8 | 4-6 | 5 | 37,520 | Chris Carpenter | Darren Oliver | Carlos Almanzar | Darren Oliver | Randy Myers | 44 | 61 | -17 |
| 1998-04-12 | @ TEX | 11 | L 1-3 | 4-7 | 5 | 28,435 | Erik Hanson | John Burkett | John Wetteland | Paul Quantrill | | 45 | 64 | -19 |
| 1998-04-13 | @ KCA | 12 | L 1-11 | 4-8 | 5 | 11,749 | Pat Hentgen | Glendon Rusch | Glendon Rusch | Pat Hentgen | | 46 | 75 | -29 |
| 1998-04-14 | @ KCA | 13 | W 5-1 | 5-8 | 5 | 11,194 | Juan Guzman | Pat Rapp | Juan Guzman | Pat Rapp | Paul Quantrill | 51 | 76 | -25 |
| 1998-04-15 | @ KCA | 14 | L 3-7 | 5-9 | 5 | 11,316 | Woody Williams | Chris Haney | Chris Haney | Woody Williams | | 54 | 83 | -29 |
| 1998-04-17 | vs CHA | 15 | W 6-1 | 6-9 | 5 | 28,240 | Roger Clemens | Jason Bere | Roger Clemens | Jason Bere | | 60 | 84 | -24 |
| 1998-04-18 | vs CHA | 16 | W 9-4 | 7-9 | 5 | 29,065 | Pat Hentgen | Jaime Navarro | Pat Hentgen | Jaime Navarro | | 69 | 88 | -19 |
| 1998-04-19 | vs CHA | 17 | W 5-4 | 8-9 | 5 | 31,265 | Juan Guzman | Scott Eyre | Chris Carpenter | Carlos Castillo | | 74 | 92 | -18 |
| 1998-04-20 | vs NYA | 18 | L 2-3 | 8-10 | 5 | 26,385 | Woody Williams | David Wells | Willie Banks | Bill Risley | Mike Stanton | 76 | 95 | -19 |
| 1998-04-21 | vs NYA | 19 | L 3-5 | 8-11 | 5 | 27,192 | Erik Hanson | Ramiro Mendoza | Mike Stanton | Dan Plesac | | 79 | 100 | -21 |
| 1998-04-22 | vs NYA | 20 | L 1-9 | 8-12 | 5 | 29,164 | Roger Clemens | Andy Pettitte | Andy Pettitte | Roger Clemens | | 80 | 109 | -29 |
| 1998-04-24 | @ CHA | 21 | W 3-1 | 9-12 | 5 | 14,198 | Pat Hentgen | Jaime Navarro | Pat Hentgen | Jaime Navarro | Randy Myers | 83 | 110 | -27 |
| 1998-04-25 | @ CHA | 22 | L 1-8 | 9-13 | 5 | 14,457 | Juan Guzman | Scott Eyre | Scott Eyre | Juan Guzman | | 84 | 118 | -34 |
| 1998-04-26 | @ CHA | 23 | L 5-5 | 9-14 | 5 | 13,705 | Erik Hanson | James Baldwin | | | | 89 | 123 | -34 |
| 1998-04-27 | @ NYA | 24 | L 0-1 | 9-15 | 5 | 17,863 | Roger Clemens | Andy Pettitte | Andy Pettitte | Roger Clemens | Mariano Rivera | 89 | 124 | -35 |
| 1998-04-28 | @ NYA | 25 | W 5-2 | 10-15 | 5 | 18,727 | Woody Williams | Ramiro Mendoza | Woody Williams | Ramiro Mendoza | Randy Myers | 94 | 126 | -32 |
| 1998-04-29 | vs KCA | 26 | L 2-7 | 10-16 | 5 | 25,644 | Pat Hentgen | Hipolito Pichardo | Hipolito Pichardo | Pat Hentgen | | 96 | 133 | -37 |
| 1998-04-30 | vs KCA | 27 | L 4-7 | 10-17 | 5 | 26,690 | Juan Guzman | Glendon Rusch | Glendon Rusch | Juan Guzman | Jeff Montgomery | 100 | 140 | -40 |
| 1998-05-01 | @ OAK | 28 | L 2-5 | 10-18 | 5 | 7,078 | Erik Hanson | Tom Candiotti | Tom Candiotti | Erik Hanson | Billy Taylor | 102 | 145 | -43 |
| 1998-05-02 | @ OAK | 29 | W 7-0 | 11-18 | 5 | 10,729 | Roger Clemens | Mike Oquist | Roger Clemens | Mike Oquist | | 109 | 145 | -36 |
| 1998-05-03 | @ OAK | 30 | W 6-3 | 12-18 | 5 | 23,463 | Woody Williams | Dave Telgheder | Woody Williams | Dave Telgheder | Randy Myers | 115 | 148 | -33 |
| 1998-05-04 | @ OAK | 31 | L 4-7 | 12-19 | 5 | 5,206 | Pat Hentgen | Kenny Rogers | Kenny Rogers | Pat Hentgen | | 119 | 155 | -36 |
| 1998-05-05 | @ ANA | 32 | W 13-11 | 13-19 | 4 | 17,271 | Juan Guzman | Ken Hill | Dan Plesac | Troy Percival | Randy Myers | 132 | 166 | -34 |
| 1998-05-06 | @ ANA | 33 | W 6-5 | 14-19 | 4 | 17,392 | Erik Hanson | Omar Olivares | Kelvim Escobar | Shigetoshi Hasegawa | Randy Myers | 138 | 171 | -33 |
| 1998-05-07 | @ SEA | 34 | W 6-0 | 15-19 | 4 | 24,129 | Roger Clemens | Jamie Moyer | Roger Clemens | Jamie Moyer | | 144 | 171 | -27 |
| 1998-05-08 | @ SEA | 35 | L 3-8 | 15-20 | 4 | 29,920 | Woody Williams | Randy Johnson | Randy Johnson | Woody Williams | | 147 | 179 | -32 |
| 1998-05-09 | @ SEA | 36 | W 4-1 | 16-20 | 4 | 49,851 | Pat Hentgen | Bill Swift | Pat Hentgen | Bill Swift | Randy Myers | 151 | 180 | -29 |
| 1998-05-10 | @ SEA | 37 | L 1-3 | 16-21 | 4 | 39,249 | Juan Guzman | Jeff Fassero | Jeff Fassero | Juan Guzman | Bobby Ayala | 152 | 183 | -31 |
| 1998-05-12 | vs OAK | 38 | W 4-3 | 17-21 | 4 | 25,636 | Erik Hanson | Tom Candiotti | Randy Myers | Billy Taylor | | 156 | 186 | -30 |
| 1998-05-13 | vs OAK | 39 | L 2-4 | 17-22 | 4 | 25,732 | Roger Clemens | Jimmy Haynes | Jimmy Haynes | Roger Clemens | Mike Fetters | 158 | 190 | -32 |
| 1998-05-14 | vs ANA | 40 | W 5-4 | 18-22 | 4 | 25,606 | Woody Williams | Chuck Finley | Randy Myers | Rich DeLucia | | 163 | 194 | -31 |
| 1998-05-15 | vs ANA | 41 | W 9-1 | 19-22 | 4 | 26,644 | Pat Hentgen | Ken Hill | Pat Hentgen | Ken Hill | | 172 | 195 | -23 |
| 1998-05-16 | vs SEA | 42 | L 1-8 | 19-23 | 4 | 31,121 | Juan Guzman | Jeff Fassero | Jeff Fassero | Juan Guzman | | 173 | 203 | -30 |
| 1998-05-17 | vs SEA | 43 | W 4-3 | 20-23 | 4 | 28,111 | Erik Hanson | Jamie Moyer | Dan Plesac | Heathcliff Slocumb | | 177 | 206 | -29 |
| 1998-05-18 | vs SEA | 44 | L 4-9 | 20-24 | 5 | 28,125 | Roger Clemens | Ken Cloude | Paul Spoljaric | Roger Clemens | | 181 | 215 | -34 |
| 1998-05-19 | vs TBA | 45 | W 3-1 | 21-24 | 3 | 25,662 | Woody Williams | Dennis Springer | Woody Williams | Dennis Springer | Randy Myers | 184 | 216 | -32 |
| 1998-05-20 | vs TBA | 46 | W 9-1 | 22-24 | 3 | 26,107 | Pat Hentgen | Wilson Alvarez | Pat Hentgen | Wilson Alvarez | | 193 | 217 | -24 |
| 1998-05-21 | vs TBA | 47 | W 6-1 | 23-24 | 3 | 30,108 | Juan Guzman | Rolando Arrojo | Juan Guzman | Rolando Arrojo | | 199 | 218 | -19 |
| 1998-05-22 | @ CLE | 48 | L 7-9 | 23-25 | 3 | 43,269 | Erik Hanson | Dave Burba | Dave Burba | Erik Hanson | Michael Jackson | 206 | 227 | -21 |
| 1998-05-23 | @ CLE | 49 | W 7-2 | 24-25 | 3 | 43,306 | Roger Clemens | Bartolo Colon | Roger Clemens | Bartolo Colon | | 213 | 229 | -16 |
| 1998-05-24 | @ CLE | 50 | W 5-0 | 25-25 | 3 | 43,194 | Woody Williams | Dwight Gooden | Woody Williams | Dwight Gooden | | 218 | 229 | -11 |
| 1998-05-25 | @ BOS | 51 | W 7-5 | 26-25 | 3 | 32,342 | Pat Hentgen | Pedro Martinez | Pat Hentgen | Pedro Martinez | Randy Myers | 225 | 234 | -9 |
| 1998-05-26 | @ BOS | 52 | W 5-2 | 27-25 | 3 | 27,668 | Juan Guzman | Steve Avery | Juan Guzman | Steve Avery | Randy Myers | 230 | 236 | -6 |
| 1998-05-28 | vs CLE | 53 | L 2-6 | 27-26 | 3 | 30,282 | Chris Carpenter | Dave Burba | Dave Burba | Chris Carpenter | | 232 | 242 | -10 |
| 1998-05-29 | vs CLE | 54 | L 3-7 | 27-27 | 3 | 29,085 | Roger Clemens | Bartolo Colon | Bartolo Colon | Roger Clemens | | 235 | 249 | -14 |
| 1998-05-30 | vs CLE | 55 | W 4-2 | 28-27 | 3 | 37,179 | Woody Williams | Dwight Gooden | Woody Williams | Dwight Gooden | Randy Myers | 239 | 251 | -12 |
| 1998-05-31 | vs CLE | 56 | L 3-8 | 28-28 | 3 | 30,090 | Pat Hentgen | Charles Nagy | Charles Nagy | Pat Hentgen | Jose Mesa | 242 | 259 | -17 |
| 1998-06-01 | vs BOS | 57 | L 5-9 | 28-29 | 3 | 27,372 | Juan Guzman | Tim Wakefield | Jim Corsi | Randy Myers | | 247 | 268 | -21 |
| 1998-06-02 | vs BOS | 58 | L 3-11 | 28-30 | 3 | 26,177 | Chris Carpenter | Steve Avery | Steve Avery | Chris Carpenter | | 250 | 279 | -29 |
| 1998-06-03 | vs DET | 59 | W 5-1 | 29-30 | 3 | 26,291 | Roger Clemens | Seth Greisinger | Roger Clemens | Seth Greisinger | | 255 | 280 | -25 |
| 1998-06-04 | vs DET | 60 | W 9-6 | 30-30 | 3 | 34,408 | Woody Williams | Brian Moehler | Woody Williams | Brian Moehler | Randy Myers | 264 | 286 | -22 |
| 1998-06-05 | vs PHI | 61 | L 7-8 | 30-31 | 3 | 31,176 | Pat Hentgen | Tyler Green | Tyler Green | Bill Risley | Mark Leiter | 271 | 294 | -23 |
| 1998-06-06 | vs PHI | 62 | L 6-10 | 30-32 | 3 | 30,102 | Juan Guzman | Mark Portugal | Wayne Gomes | Juan Guzman | | 277 | 304 | -27 |
| 1998-06-07 | vs PHI | 63 | W 3-1 | 31-32 | 3 | 26,236 | Chris Carpenter | Curt Schilling | Chris Carpenter | Curt Schilling | Randy Myers | 280 | 305 | -25 |
| 1998-06-08 | @ FLO | 64 | L 3-4 | 31-33 | 3 | 17,414 | Roger Clemens | Brian Meadows | Brian Edmondson | Erik Hanson | | 283 | 309 | -26 |
| 1998-06-09 | @ FLO | 65 | L 4-5 | 31-34 | 3 | 14,591 | Woody Williams | Livan Hernandez | Livan Hernandez | Paul Quantrill | | 287 | 314 | -27 |
| 1998-06-10 | @ FLO | 66 | W 4-3 | 32-34 | 3 | 16,994 | Pat Hentgen | Joe Fontenot | Robert Person | Jay Powell | Randy Myers | 291 | 317 | -26 |
| 1998-06-12 | vs BAL | 67 | L 5-9 | 32-35 | 4 | 30,237 | Juan Guzman | Mike Mussina | Mike Mussina | Juan Guzman | | 296 | 326 | -30 |
| 1998-06-13 | vs BAL | 68 | W 9-8 | 33-35 | 3 | 38,102 | Chris Carpenter | Doug Drabek | Robert Person | Doug Drabek | Randy Myers | 305 | 334 | -29 |
| 1998-06-14 | vs BAL | 69 | W 7-4 | 34-35 | 3 | 28,132 | Roger Clemens | Pete Smith | Roger Clemens | Pete Smith | Randy Myers | 312 | 338 | -26 |
| 1998-06-15 | @ TBA | 70 | L 7-8 | 34-36 | 3 | 24,122 | Woody Williams | Julio Santana | Rick White | Paul Quantrill | Roberto Hernandez | 319 | 346 | -27 |
| 1998-06-16 | @ TBA | 71 | L 3-4 | 34-37 | 4 | 24,278 | Pat Hentgen | Jason Johnson | Jim Mecir | Randy Myers | | 322 | 350 | -28 |
| 1998-06-17 | @ TBA | 72 | L 1-2 | 34-38 | 4 | 24,394 | Juan Guzman | Rolando Arrojo | Rolando Arrojo | Juan Guzman | Roberto Hernandez | 323 | 352 | -29 |
| 1998-06-18 | @ BAL | 73 | W 13-6 | 35-38 | 3 | 47,374 | Chris Carpenter | Doug Johns | Chris Carpenter | Doug Johns | | 336 | 358 | -22 |
| 1998-06-19 | @ BAL | 74 | L 4-7 | 35-39 | 4 | 47,012 | Roger Clemens | Pete Smith | Norm Charlton | Bill Risley | | 340 | 365 | -25 |
| 1998-06-20 | @ BAL | 75 | L 3-11 | 35-40 | 4 | 48,011 | Woody Williams | Scott Erickson | Scott Erickson | Woody Williams | | 343 | 376 | -33 |
| 1998-06-21 | @ BAL | 76 | W 7-3 | 36-40 | 4 | 47,522 | Pat Hentgen | Sidney Ponson | Pat Hentgen | Sidney Ponson | Randy Myers | 350 | 379 | -29 |
| 1998-06-22 | vs MON | 77 | W 14-2 | 37-40 | 4 | 33,132 | Juan Guzman | Carl Pavano | Juan Guzman | Carl Pavano | | 364 | 381 | -17 |
| 1998-06-23 | vs MON | 78 | W 3-2 | 38-40 | 3 | 33,492 | Chris Carpenter | Javier Vazquez | Chris Carpenter | Miguel Batista | Randy Myers | 367 | 383 | -16 |
| 1998-06-24 | @ MON | 79 | W 7-6 | 39-40 | 3 | 16,515 | Roger Clemens | Shawn Boskie | Roger Clemens | Shawn Boskie | Randy Myers | 374 | 389 | -15 |
| 1998-06-25 | @ MON | 80 | W 1-0 | 40-40 | 3 | 9,256 | Woody Williams | Carlos Perez | Woody Williams | Carlos Perez | | 375 | 389 | -14 |
| 1998-06-26 | @ ATL | 81 | W 6-4 | 41-40 | 3 | 47,081 | Pat Hentgen | John Smoltz | Pat Hentgen | John Smoltz | Randy Myers | 381 | 393 | -12 |
| 1998-06-27 | @ ATL | 82 | L 0-2 | 41-41 | 3 | 48,338 | Juan Guzman | Greg Maddux | Greg Maddux | Juan Guzman | | 381 | 395 | -14 |
| 1998-06-28 | @ ATL | 83 | L 3-10 | 41-42 | 3 | 44,185 | Chris Carpenter | Tom Glavine | Tom Glavine | Chris Carpenter | | 384 | 405 | -21 |
| 1998-06-30 | vs NYN | 84 | W 6-3 | 42-42 | 3 | 30,322 | Roger Clemens | Rick Reed | Roger Clemens | Rick Reed | | 390 | 408 | -18 |
| 1998-07-01 | vs NYN | 85 | W 15-10 | 43-42 | 3 | 37,252 | Woody Williams | Hideo Nomo | Dan Plesac | Mel Rojas | | 405 | 418 | -13 |
| 1998-07-02 | vs NYN | 86 | L 1-9 | 43-43 | 3 | 27,325 | Pat Hentgen | Bobby Jones | Bobby Jones | Pat Hentgen | | 406 | 427 | -21 |
| 1998-07-03 | vs TBA | 87 | W 3-2 | 44-43 | 3 | 25,625 | Juan Guzman | Jason Johnson | Randy Myers | Esteban Yan | | 409 | 429 | -20 |
| 1998-07-04 | vs TBA | 88 | W 8-0 | 45-43 | 3 | 29,198 | Chris Carpenter | Dennis Springer | Chris Carpenter | Dennis Springer | | 417 | 429 | -12 |
| 1998-07-05 | vs TBA | 89 | W 2-1 | 46-43 | 3 | 31,240 | Roger Clemens | Tony Saunders | Paul Quantrill | Rick White | Randy Myers | 419 | 430 | -11 |
| 1998-07-09 | @ DET | 90 | L 3-4 | 46-44 | 3 | 16,012 | Woody Williams | Justin Thompson | Matt Anderson | Dan Plesac | Todd Jones | 422 | 434 | -12 |
| 1998-07-10 | @ DET | 91 | L 2-3 | 46-45 | 3 | 23,394 | Pat Hentgen | Seth Greisinger | Todd Jones | Paul Quantrill | | 424 | 437 | -13 |
| 1998-07-11 | @ DET | 92 | L 2-5 | 46-46 | 3 | 21,072 | Chris Carpenter | Brian Moehler | Brian Moehler | Chris Carpenter | Sean Runyan | 426 | 442 | -16 |
| 1998-07-12 | @ DET | 93 | W 7-2 | 47-46 | 3 | 20,231 | Roger Clemens | Brian Powell | Roger Clemens | Doug Brocail | | 433 | 444 | -11 |
| 1998-07-13 | @ BAL | 94 | L 0-5 | 47-47 | 3 | 41,474 | Juan Guzman | Nerio Rodriguez | Nerio Rodriguez | Juan Guzman | | 433 | 449 | -16 |
| 1998-07-14 | @ BAL | 95 | L 5-11 | 47-48 | 3 | 44,122 | Woody Williams | Mike Mussina | Mike Mussina | Woody Williams | | 438 | 460 | -22 |
| 1998-07-15 | @ CHA | 96 | L 3-9 | 47-50 | 3 | 0 | Pat Hentgen | Jaime Navarro | Jaime Navarro | Pat Hentgen | | 441 | 469 | -28 |
| 1998-07-15 | @ CHA | 97 | L 2-5 | 47-50 | 3 | 15,602 | Dave Stieb | Carlos Castillo | Carlos Castillo | Dave Stieb | Bill Simas | 443 | 474 | -31 |
| 1998-07-16 | @ CHA | 98 | W 5-2 | 48-50 | 3 | 19,638 | Chris Carpenter | James Baldwin | Chris Carpenter | James Baldwin | Randy Myers | 448 | 476 | -28 |
| 1998-07-17 | vs NYA | 99 | W 9-6 | 49-50 | 3 | 39,172 | Roger Clemens | Ramiro Mendoza | Roger Clemens | Darren Holmes | Randy Myers | 457 | 482 | -25 |
| 1998-07-18 | vs NYA | 100 | L 3-10 | 49-51 | 3 | 48,123 | Juan Guzman | Orlando Hernandez | Orlando Hernandez | Juan Guzman | | 460 | 492 | -32 |
| 1998-07-19 | vs NYA | 101 | W 9-3 | 50-51 | 3 | 42,176 | Woody Williams | Andy Pettitte | Woody Williams | Andy Pettitte | | 469 | 495 | -26 |
| 1998-07-21 | vs CHA | 102 | L 3-6 | 50-52 | 3 | 30,209 | Pat Hentgen | James Baldwin | James Baldwin | Pat Hentgen | Bill Simas | 472 | 501 | -29 |
| 1998-07-22 | vs CHA | 103 | W 4-0 | 51-52 | 3 | 29,221 | Roger Clemens | Jim Parque | Roger Clemens | Jim Parque | | 476 | 501 | -25 |
| 1998-07-23 | @ BOS | 104 | L 7-8 | 51-53 | 4 | 33,011 | Chris Carpenter | Jin Ho Cho | Tom Gordon | Randy Myers | | 483 | 509 | -26 |
| 1998-07-24 | @ BOS | 105 | W 10-6 | 52-53 | 4 | 33,159 | Juan Guzman | Steve Avery | Juan Guzman | Steve Avery | Paul Quantrill | 493 | 515 | -22 |
| 1998-07-25 | @ BOS | 106 | L 3-5 | 52-54 | 4 | 33,099 | Woody Williams | Bret Saberhagen | Derek Lowe | Woody Williams | Tom Gordon | 496 | 520 | -24 |
| 1998-07-26 | @ BOS | 107 | L 3-6 | 52-55 | 4 | 33,059 | Pat Hentgen | Pedro Martinez | Pedro Martinez | Pat Hentgen | | 499 | 526 | -27 |
| 1998-07-28 | vs TEX | 108 | W 8-3 | 53-55 | 4 | 29,177 | Roger Clemens | Aaron Sele | Roger Clemens | Aaron Sele | | 507 | 529 | -22 |
| 1998-07-29 | vs TEX | 109 | L 6-9 | 53-56 | 4 | 28,220 | Chris Carpenter | Darren Oliver | Darren Oliver | Chris Carpenter | John Wetteland | 513 | 538 | -25 |
| 1998-07-30 | vs TEX | 110 | W 1-0 | 54-56 | 4 | 29,264 | Juan Guzman | Esteban Loaiza | Juan Guzman | Esteban Loaiza | Randy Myers | 514 | 538 | -24 |
| 1998-07-31 | @ MIN | 111 | L 4-6 | 54-57 | 4 | 26,054 | Woody Williams | Frankie Rodriguez | Frankie Rodriguez | Woody Williams | Rick Aguilera | 518 | 544 | -26 |
| 1998-08-01 | @ MIN | 112 | W 10-9 | 55-57 | 4 | 17,128 | Pat Hentgen | LaTroy Hawkins | Pat Hentgen | LaTroy Hawkins | Randy Myers | 528 | 553 | -25 |
| 1998-08-02 | @ MIN | 113 | W 6-4 | 56-57 | 4 | 40,096 | Roger Clemens | Brad Radke | Roger Clemens | Brad Radke | Randy Myers | 534 | 557 | -23 |
| 1998-08-04 | @ TEX | 114 | L 9-11 | 56-58 | 4 | 45,213 | Chris Carpenter | Todd Stottlemyre | Todd Stottlemyre | Chris Carpenter | John Wetteland | 543 | 568 | -25 |
| 1998-08-05 | @ TEX | 115 | L 3-4 | 56-59 | 4 | 27,766 | Kelvim Escobar | Esteban Loaiza | John Wetteland | Randy Myers | | 546 | 572 | -26 |
| 1998-08-07 | vs OAK | 116 | L 6-7 | 56-60 | 4 | 31,286 | Woody Williams | Jimmy Haynes | Jimmy Haynes | Woody Williams | Mike Fetters | 552 | 579 | -27 |
| 1998-08-08 | vs OAK | 117 | W 6-5 | 57-60 | 4 | 31,330 | Pat Hentgen | Blake Stein | Dan Plesac | Mike Fetters | | 558 | 584 | -26 |
| 1998-08-09 | vs OAK | 118 | W 4-3 | 58-60 | 4 | 30,114 | Roger Clemens | Mike Oquist | Paul Quantrill | Mike Mohler | | 562 | 587 | -25 |
| 1998-08-11 | vs SEA | 119 | W 7-4 | 59-60 | 4 | 33,137 | Chris Carpenter | Jeff Fassero | Chris Carpenter | Jeff Fassero | Paul Quantrill | 569 | 591 | -22 |
| 1998-08-12 | vs SEA | 120 | W 11-5 | 60-60 | 4 | 39,139 | Kelvim Escobar | Jamie Moyer | Nerio Rodriguez | Bobby Ayala | | 580 | 596 | -16 |
| 1998-08-13 | vs ANA | 121 | W 4-3 | 61-60 | 4 | 26,481 | Woody Williams | Chuck Finley | Bill Risley | Shigetoshi Hasegawa | Dan Plesac | 584 | 599 | -15 |
| 1998-08-14 | vs ANA | 122 | L 5-7 | 61-61 | 4 | 27,276 | Pat Hentgen | Allen Watson | Allen Watson | Pat Hentgen | Troy Percival | 589 | 606 | -17 |
| 1998-08-15 | vs ANA | 123 | L 3-6 | 61-62 | 4 | 30,379 | Roger Clemens | Omar Olivares | Rich DeLucia | Steve Sinclair | | 592 | 612 | -20 |
| 1998-08-16 | vs ANA | 124 | W 6-4 | 62-62 | 4 | 29,259 | Chris Carpenter | Jeff Juden | Chris Carpenter | Jeff Juden | Paul Quantrill | 598 | 616 | -18 |
| 1998-08-17 | @ OAK | 125 | W 4-2 | 63-62 | 4 | 9,761 | Kelvim Escobar | Tom Candiotti | Kelvim Escobar | Tom Candiotti | Dan Plesac | 602 | 618 | -16 |
| 1998-08-18 | @ OAK | 126 | L 5-10 | 63-63 | 4 | 9,086 | Woody Williams | Jimmy Haynes | Jimmy Haynes | Woody Williams | | 607 | 628 | -21 |
| 1998-08-19 | @ SEA | 127 | W 16-2 | 64-63 | 4 | 26,258 | Pat Hentgen | Ken Cloude | Pat Hentgen | Ken Cloude | Dave Stieb | 623 | 630 | -7 |
| 1998-08-20 | @ SEA | 128 | W 7-0 | 65-63 | 4 | 26,642 | Roger Clemens | Bill Swift | Roger Clemens | Bill Swift | | 630 | 630 | 0 |
| 1998-08-21 | @ ANA | 129 | W 9-4 | 66-63 | 4 | 36,052 | Chris Carpenter | Jeff Juden | Chris Carpenter | Jeff Juden | | 639 | 634 | 5 |
| 1998-08-22 | @ ANA | 130 | L 1-5 | 66-64 | 4 | 42,882 | Kelvim Escobar | Steve Sparks | Steve Sparks | Kelvim Escobar | Shigetoshi Hasegawa | 640 | 639 | 1 |
| 1998-08-23 | @ ANA | 131 | L 2-3 | 66-65 | 4 | 34,142 | Woody Williams | Chuck Finley | Chuck Finley | Carlos Almanzar | Troy Percival | 642 | 642 | 0 |
| 1998-08-24 | vs KCA | 132 | L 3-7 | 66-66 | 4 | 26,306 | Pat Hentgen | Brian Barber | Brian Barber | Pat Hentgen | Matt Whisenant | 645 | 649 | -4 |
| 1998-08-25 | vs KCA | 133 | W 3-0 | 67-66 | 4 | 26,173 | Roger Clemens | Chris Haney | Roger Clemens | Chris Haney | | 648 | 649 | -1 |
| 1998-08-26 | vs KCA | 134 | L 2-7 | 67-67 | 4 | 25,557 | Chris Carpenter | Tim Belcher | Tim Belcher | Chris Carpenter | | 650 | 656 | -6 |
| 1998-08-27 | vs KCA | 135 | W 11-1 | 68-67 | 4 | 25,524 | Kelvim Escobar | Jose Rosado | Kelvim Escobar | Jose Rosado | | 661 | 657 | 4 |
| 1998-08-28 | vs MIN | 136 | W 7-6 | 69-67 | 4 | 26,268 | Woody Williams | LaTroy Hawkins | Woody Williams | Mike Trombley | Dan Plesac | 668 | 663 | 5 |
| 1998-08-29 | vs MIN | 137 | W 14-7 | 70-67 | 4 | 30,101 | Dave Stieb | Brad Radke | Dave Stieb | Brad Radke | | 682 | 670 | 12 |
| 1998-08-30 | vs MIN | 138 | W 6-0 | 71-67 | 3 | 29,202 | Roger Clemens | Frankie Rodriguez | Roger Clemens | Frankie Rodriguez | | 688 | 670 | 18 |
| 1998-09-01 | @ KCA | 139 | W 2-1 | 72-67 | 3 | 12,447 | Chris Carpenter | Tim Belcher | Chris Carpenter | Tim Belcher | Paul Quantrill | 690 | 671 | 19 |
| 1998-09-02 | @ KCA | 140 | W 5-0 | 73-67 | 3 | 12,541 | Kelvim Escobar | Jose Rosado | Kelvim Escobar | Jose Rosado | Paul Quantrill | 695 | 671 | 24 |
| 1998-09-03 | vs BOS | 141 | W 4-3 | 74-67 | 3 | 27,226 | Woody Williams | Pedro Martinez | Robert Person | Dario Veras | | 699 | 674 | 25 |
| 1998-09-04 | vs BOS | 142 | W 12-1 | 75-67 | 3 | 29,166 | Pat Hentgen | Tim Wakefield | Pat Hentgen | Tim Wakefield | Dave Stieb | 711 | 675 | 36 |
| 1998-09-05 | vs BOS | 143 | W 4-3 | 76-67 | 3 | 37,158 | Roger Clemens | Bret Saberhagen | Roger Clemens | Bret Saberhagen | Paul Quantrill | 715 | 678 | 37 |
| 1998-09-06 | vs BOS | 144 | W 8-7 | 77-67 | 3 | 38,374 | Chris Carpenter | Pete Schourek | Paul Quantrill | Derek Lowe | Robert Person | 723 | 685 | 38 |
| 1998-09-07 | vs CLE | 145 | W 15-1 | 78-67 | 3 | 31,089 | Kelvim Escobar | Chad Ogea | Kelvim Escobar | Chad Ogea | | 738 | 686 | 52 |
| 1998-09-09 | vs CLE | 146 | L 3-6 | 78-68 | 3 | 32,157 | Woody Williams | Dwight Gooden | Doug Jones | Carlos Almanzar | Michael Jackson | 741 | 692 | 49 |
| 1998-09-10 | @ NYA | 147 | L 5-8 | 78-69 | 3 | 25,881 | Pat Hentgen | Andy Pettitte | Andy Pettitte | Pat Hentgen | Darren Holmes | 746 | 700 | 46 |
| 1998-09-11 | @ NYA | 148 | W 5-4 | 79-69 | 3 | 35,856 | Roger Clemens | Hideki Irabu | Carlos Almanzar | Hideki Irabu | Robert Person | 751 | 704 | 47 |
| 1998-09-12 | @ NYA | 149 | W 5-3 | 80-69 | 3 | 48,752 | Chris Carpenter | David Wells | Chris Carpenter | David Wells | Robert Person | 756 | 707 | 49 |
| 1998-09-13 | @ NYA | 150 | W 5-3 | 81-69 | 3 | 47,471 | Kelvim Escobar | David Cone | Kelvim Escobar | David Cone | Robert Person | 761 | 710 | 51 |
| 1998-09-14 | @ CLE | 151 | L 3-6 | 81-70 | 3 | 43,152 | Woody Williams | Dwight Gooden | Dwight Gooden | Steve Sinclair | Michael Jackson | 764 | 716 | 48 |
| 1998-09-15 | @ CLE | 152 | L 5-7 | 81-71 | 3 | 43,323 | Dave Stieb | Bartolo Colon | Chad Ogea | Dave Stieb | Paul Assenmacher | 769 | 723 | 46 |
| 1998-09-16 | @ DET | 153 | W 2-1 | 82-71 | 3 | 10,967 | Roger Clemens | Brian Powell | Roger Clemens | Brian Powell | Robert Person | 771 | 724 | 47 |
| 1998-09-17 | @ DET | 154 | L 4-7 | 82-72 | 3 | 13,304 | Chris Carpenter | Bryce Florie | Doug Brocail | Robert Person | | 775 | 731 | 44 |
| 1998-09-18 | @ TBA | 155 | L 1-6 | 82-73 | 3 | 32,053 | Kelvim Escobar | Bryan Rekar | Bryan Rekar | Kelvim Escobar | | 776 | 737 | 39 |
| 1998-09-19 | @ TBA | 156 | L 5-7 | 82-74 | 3 | 35,689 | Woody Williams | Wilson Alvarez | Albie Lopez | Ben VanRyn | Roberto Hernandez | 781 | 744 | 37 |
| 1998-09-20 | @ TBA | 157 | W 7-5 | 83-74 | 3 | 32,183 | Roy Halladay | Rolando Arrojo | Bill Risley | Albie Lopez | | 788 | 749 | 39 |
| 1998-09-21 | vs BAL | 158 | W 3-1 | 84-74 | 3 | 30,380 | Roger Clemens | Scott Erickson | Roger Clemens | Scott Erickson | Dan Plesac | 791 | 750 | 41 |
| 1998-09-22 | vs BAL | 159 | W 7-3 | 85-74 | 3 | 26,363 | Chris Carpenter | Mike Mussina | Chris Carpenter | Mike Mussina | | 798 | 753 | 45 |
| 1998-09-23 | vs BAL | 160 | W 6-3 | 86-74 | 3 | 28,147 | Kelvim Escobar | Juan Guzman | Kelvim Escobar | Juan Guzman | Robert Person | 804 | 756 | 48 |
| 1998-09-25 | vs DET | 161 | L 5-7 | 86-75 | 3 | 33,151 | Woody Williams | Brian Moehler | Brian Moehler | Woody Williams | Todd Jones | 809 | 763 | 46 |
| 1998-09-26 | vs DET | 162 | W 5-4 | 87-75 | 3 | 40,268 | Roger Clemens | Seth Greisinger | Bill Risley | A.J. Sager | | 814 | 767 | 47 |
| 1998-09-27 | vs DET | 163 | W 2-1 | 88-75 | 3 | 38,036 | Roy Halladay | Justin Thompson | Roy Halladay | Justin Thompson | | 816 | 768 | 48 |