| 1998-04-01 | vs NYA | 1 | W 4-1 | 1-0 | 1 | 43,311 | Chuck Finley | Andy Pettitte | Chuck Finley | Andy Pettitte | Troy Percival | 4 | 1 | 3 |
| 1998-04-02 | vs NYA | 2 | W 10-2 | 2-0 | 1 | 29,899 | Ken Hill | David Wells | Ken Hill | David Wells | | 14 | 3 | 11 |
| 1998-04-03 | vs CLE | 3 | L 2-6 | 2-1 | 1 | 26,240 | Jack McDowell | Dave Burba | Dave Burba | Jack McDowell | | 16 | 9 | 7 |
| 1998-04-04 | vs CLE | 4 | L 0-11 | 2-2 | 1 | 34,834 | Allen Watson | Bartolo Colon | Bartolo Colon | Allen Watson | | 16 | 20 | -4 |
| 1998-04-05 | vs CLE | 5 | L 4-6 | 2-3 | 2 | 35,628 | Jason Dickson | Charles Nagy | Charles Nagy | Jason Dickson | Michael Jackson | 20 | 26 | -6 |
| 1998-04-06 | vs BOS | 6 | W 2-1 | 3-3 | 1 | 21,352 | Chuck Finley | Pedro Martinez | Mike Holtz | Tom Gordon | | 22 | 27 | -5 |
| 1998-04-07 | vs BOS | 7 | W 6-1 | 4-3 | 1 | 19,926 | Ken Hill | Tim Wakefield | Ken Hill | Tim Wakefield | | 28 | 28 | 0 |
| 1998-04-08 | vs BOS | 8 | W 2-1 | 5-3 | 1 | 24,450 | Jack McDowell | Derek Lowe | Jack McDowell | Derek Lowe | Troy Percival | 30 | 29 | 1 |
| 1998-04-10 | @ CLE | 9 | L 5-8 | 5-4 | 2 | 42,707 | Allen Watson | Bartolo Colon | Eric Plunk | Troy Percival | | 35 | 37 | -2 |
| 1998-04-11 | @ CLE | 10 | L 5-8 | 5-5 | 2 | 42,802 | Jason Dickson | Charles Nagy | Charles Nagy | Jason Dickson | Michael Jackson | 40 | 45 | -5 |
| 1998-04-12 | @ CLE | 11 | W 12-1 | 6-5 | 2 | 42,555 | Chuck Finley | Jaret Wright | Chuck Finley | Jaret Wright | | 52 | 46 | 6 |
| 1998-04-15 | @ NYA | 12 | L 3-6 | 6-6 | 2 | 40,743 | Ken Hill | David Wells | David Wells | Ken Hill | Jeff Nelson | 55 | 52 | 3 |
| 1998-04-16 | vs TBA | 13 | L 5-6 | 6-7 | 2 | 22,906 | Jack McDowell | Tony Saunders | Tony Saunders | Mike Holtz | Roberto Hernandez | 60 | 58 | 2 |
| 1998-04-17 | vs TBA | 14 | W 5-0 | 7-7 | 2 | 31,516 | Chuck Finley | Rick Gorecki | Chuck Finley | Rick Gorecki | | 65 | 58 | 7 |
| 1998-04-18 | vs TBA | 15 | L 1-8 | 7-8 | 2 | 37,878 | Jason Dickson | Wilson Alvarez | Wilson Alvarez | Jason Dickson | | 66 | 66 | 0 |
| 1998-04-19 | vs TBA | 16 | L 0-6 | 7-9 | 3 | 34,580 | Allen Watson | Rolando Arrojo | Rolando Arrojo | Allen Watson | | 66 | 72 | -6 |
| 1998-04-20 | vs BAL | 17 | W 4-3 | 8-9 | 3 | 19,217 | Ken Hill | Doug Drabek | Ken Hill | Doug Drabek | Troy Percival | 70 | 75 | -5 |
| 1998-04-21 | vs BAL | 18 | L 3-8 | 8-10 | 3 | 20,968 | Jack McDowell | Doug Johns | Arthur Rhodes | Jack McDowell | | 73 | 83 | -10 |
| 1998-04-22 | vs BAL | 19 | W 7-6 | 9-10 | 3 | 22,739 | Chuck Finley | Scott Erickson | Mike Holtz | Terry Mathews | Troy Percival | 80 | 89 | -9 |
| 1998-04-24 | @ TBA | 20 | W 10-3 | 10-10 | 2 | 27,767 | Allen Watson | Wilson Alvarez | Allen Watson | Wilson Alvarez | | 90 | 92 | -2 |
| 1998-04-25 | @ TBA | 21 | W 7-1 | 11-10 | 2 | 33,395 | Ken Hill | Rolando Arrojo | Ken Hill | Rolando Arrojo | | 97 | 93 | 4 |
| 1998-04-26 | @ TBA | 22 | W 2-1 | 12-10 | 2 | 26,882 | Jack McDowell | Dennis Springer | Omar Olivares | Dennis Springer | Troy Percival | 99 | 94 | 5 |
| 1998-04-27 | @ BAL | 23 | W 3-1 | 13-10 | 2 | 42,961 | Chuck Finley | Scott Erickson | Chuck Finley | Scott Erickson | Troy Percival | 102 | 95 | 7 |
| 1998-04-28 | @ BAL | 24 | W 6-5 | 14-10 | 2 | 41,877 | Jason Dickson | Nerio Rodriguez | Jason Dickson | Nerio Rodriguez | Troy Percival | 108 | 100 | 8 |
| 1998-04-29 | @ BOS | 25 | L 4-8 | 14-11 | 2 | 21,557 | Allen Watson | Tim Wakefield | Tim Wakefield | Allen Watson | Tom Gordon | 112 | 108 | 4 |
| 1998-04-30 | @ BOS | 26 | W 7-2 | 15-11 | 2 | 21,526 | Ken Hill | Robinson Checo | Ken Hill | Robinson Checo | | 119 | 110 | 9 |
| 1998-05-01 | vs CHA | 27 | W 7-1 | 16-11 | 2 | 36,485 | Omar Olivares | James Baldwin | Shigetoshi Hasegawa | James Baldwin | | 126 | 111 | 15 |
| 1998-05-02 | vs CHA | 28 | W 5-3 | 17-11 | 2 | 37,500 | Chuck Finley | Mike Sirotka | Rich DeLucia | Mike Sirotka | Troy Percival | 131 | 114 | 17 |
| 1998-05-03 | vs CHA | 29 | L 1-12 | 17-12 | 2 | 34,920 | Jason Dickson | Jason Bere | Jason Bere | Jason Dickson | | 132 | 126 | 6 |
| 1998-05-04 | vs CHA | 30 | L 5-6 | 17-13 | 2 | 15,997 | Allen Watson | Jaime Navarro | Tony Castillo | Rich DeLucia | Matt Karchner | 137 | 132 | 5 |
| 1998-05-05 | vs TOR | 31 | L 11-13 | 17-14 | 2 | 17,271 | Ken Hill | Juan Guzman | Dan Plesac | Troy Percival | Randy Myers | 148 | 145 | 3 |
| 1998-05-06 | vs TOR | 32 | L 5-6 | 17-15 | 2 | 17,392 | Omar Olivares | Erik Hanson | Kelvim Escobar | Shigetoshi Hasegawa | Randy Myers | 153 | 151 | 2 |
| 1998-05-08 | vs DET | 33 | W 5-3 | 18-15 | 2 | 31,064 | Allen Watson | Brian Moehler | Allen Watson | Brian Moehler | Troy Percival | 158 | 154 | 4 |
| 1998-05-09 | vs DET | 34 | L 3-7 | 18-16 | 2 | 42,409 | Chuck Finley | Frank Castillo | Frank Castillo | Chuck Finley | | 161 | 161 | 0 |
| 1998-05-10 | vs DET | 35 | W 4-2 | 19-16 | 2 | 20,354 | Ken Hill | Tim Worrell | Ken Hill | Tim Worrell | Troy Percival | 165 | 163 | 2 |
| 1998-05-12 | @ CHA | 36 | L 2-5 | 19-17 | 2 | 13,050 | Omar Olivares | Scott Eyre | Carlos Castillo | Omar Olivares | | 167 | 168 | -1 |
| 1998-05-13 | @ CHA | 37 | W 8-3 | 20-17 | 2 | 13,498 | Allen Watson | Mike Sirotka | Allen Watson | Mike Sirotka | | 175 | 171 | 4 |
| 1998-05-14 | @ TOR | 38 | L 4-5 | 20-18 | 2 | 25,606 | Chuck Finley | Woody Williams | Randy Myers | Rich DeLucia | | 179 | 176 | 3 |
| 1998-05-15 | @ TOR | 39 | L 1-9 | 20-19 | 2 | 26,644 | Ken Hill | Pat Hentgen | Pat Hentgen | Ken Hill | | 180 | 185 | -5 |
| 1998-05-16 | @ DET | 40 | W 8-6 | 21-19 | 2 | 18,320 | Jason Dickson | Tim Worrell | Jason Dickson | Tim Worrell | Troy Percival | 188 | 191 | -3 |
| 1998-05-17 | @ DET | 41 | L 3-4 | 21-20 | 2 | 13,476 | Omar Olivares | Justin Thompson | Bryce Florie | Rich DeLucia | Todd Jones | 191 | 195 | -4 |
| 1998-05-18 | @ DET | 42 | L 2-11 | 21-21 | 2 | 10,236 | Allen Watson | Brian Moehler | Brian Moehler | Allen Watson | | 193 | 206 | -13 |
| 1998-05-19 | vs OAK | 43 | W 4-3 | 22-21 | 2 | 17,275 | Chuck Finley | Kenny Rogers | Shigetoshi Hasegawa | Billy Taylor | | 197 | 209 | -12 |
| 1998-05-20 | vs OAK | 44 | W 5-4 | 23-21 | 2 | 17,160 | Ken Hill | Mike Oquist | Ken Hill | Mike Oquist | Troy Percival | 202 | 213 | -11 |
| 1998-05-21 | vs OAK | 45 | W 12-2 | 24-21 | 2 | 20,075 | Jack McDowell | Blake Stein | Jason Dickson | Blake Stein | | 214 | 215 | -1 |
| 1998-05-22 | vs MIN | 46 | W 10-3 | 25-21 | 2 | 34,363 | Omar Olivares | Bob Tewksbury | Omar Olivares | Bob Tewksbury | | 224 | 218 | 6 |
| 1998-05-23 | vs MIN | 47 | L 5-9 | 25-22 | 2 | 31,036 | Allen Watson | LaTroy Hawkins | LaTroy Hawkins | Allen Watson | Greg Swindell | 229 | 227 | 2 |
| 1998-05-24 | vs MIN | 48 | L 1-9 | 25-23 | 2 | 24,728 | Chuck Finley | Brad Radke | Brad Radke | Chuck Finley | | 230 | 236 | -6 |
| 1998-05-25 | vs KCA | 49 | L 4-6 | 25-24 | 2 | 21,065 | Ken Hill | Tim Belcher | Tim Belcher | Ken Hill | Jeff Montgomery | 234 | 242 | -8 |
| 1998-05-27 | vs KCA | 50 | L 0-4 | 25-25 | 2 | 17,810 | Omar Olivares | Jose Rosado | Jose Rosado | Omar Olivares | | 234 | 246 | -12 |
| 1998-05-29 | @ MIN | 51 | W 3-1 | 26-25 | 2 | 14,633 | Chuck Finley | LaTroy Hawkins | Chuck Finley | LaTroy Hawkins | Troy Percival | 237 | 247 | -10 |
| 1998-05-30 | @ MIN | 52 | L 1-8 | 26-26 | 2 | 16,827 | Ken Hill | Brad Radke | Brad Radke | Ken Hill | | 238 | 255 | -17 |
| 1998-05-31 | @ MIN | 53 | W 6-5 | 27-26 | 2 | 11,285 | Jack McDowell | Mike Morgan | Jason Dickson | Greg Swindell | Troy Percival | 244 | 260 | -16 |
| 1998-06-01 | @ KCA | 54 | W 6-3 | 28-26 | 2 | 14,502 | Omar Olivares | Jose Rosado | Shigetoshi Hasegawa | Hipolito Pichardo | Troy Percival | 250 | 263 | -13 |
| 1998-06-02 | @ KCA | 55 | W 7-5 | 29-26 | 2 | 12,020 | Jarrod Washburn | Chris Haney | Jarrod Washburn | Chris Haney | Troy Percival | 257 | 268 | -11 |
| 1998-06-03 | @ SEA | 56 | W 8-1 | 30-26 | 2 | 24,944 | Chuck Finley | Randy Johnson | Chuck Finley | Randy Johnson | | 265 | 269 | -4 |
| 1998-06-04 | @ SEA | 57 | W 6-2 | 31-26 | 2 | 23,709 | Ken Hill | Ken Cloude | Ken Hill | Ken Cloude | Shigetoshi Hasegawa | 271 | 271 | 0 |
| 1998-06-05 | vs COL | 58 | W 5-0 | 32-26 | 2 | 39,621 | Jason Dickson | Bobby Jones | Jason Dickson | Bobby Jones | | 276 | 271 | 5 |
| 1998-06-06 | vs COL | 59 | W 2-1 | 33-26 | 2 | 38,671 | Omar Olivares | Darryl Kile | Omar Olivares | Darryl Kile | Troy Percival | 278 | 272 | 6 |
| 1998-06-07 | vs COL | 60 | W 6-5 | 34-26 | 2 | 42,493 | Jarrod Washburn | Jamey Wright | Greg Cadaret | Jerry DiPoto | | 284 | 277 | 7 |
| 1998-06-09 | @ ARI | 61 | W 10-8 | 35-26 | 2 | 43,074 | Chuck Finley | Willie Blair | Chuck Finley | Clint Sodowsky | Troy Percival | 294 | 285 | 9 |
| 1998-06-10 | @ ARI | 62 | L 2-10 | 35-27 | 2 | 40,819 | Ken Hill | Omar Daal | Omar Daal | Ken Hill | | 296 | 295 | 1 |
| 1998-06-11 | @ ARI | 63 | W 10-5 | 36-27 | 2 | 41,954 | Jason Dickson | Bob Wolcott | Jason Dickson | Bob Wolcott | Troy Percival | 306 | 300 | 6 |
| 1998-06-12 | @ TEX | 64 | W 5-1 | 37-27 | 2 | 35,505 | Omar Olivares | John Burkett | Omar Olivares | John Burkett | Greg Cadaret | 311 | 301 | 10 |
| 1998-06-13 | @ TEX | 65 | W 18-6 | 38-27 | 2 | 46,289 | Jarrod Washburn | Aaron Sele | Jarrod Washburn | Aaron Sele | | 329 | 307 | 22 |
| 1998-06-14 | @ TEX | 66 | L 2-4 | 38-28 | 2 | 36,648 | Chuck Finley | Rick Helling | Rick Helling | Chuck Finley | John Wetteland | 331 | 311 | 20 |
| 1998-06-15 | @ TEX | 67 | W 8-5 | 39-28 | 2 | 43,380 | Steve Sparks | Bobby Witt | Steve Sparks | Bobby Witt | Troy Percival | 339 | 316 | 23 |
| 1998-06-16 | vs SEA | 68 | W 3-2 | 40-28 | 1 | 23,123 | Jason Dickson | Bill Swift | Jason Dickson | Bill Swift | Troy Percival | 342 | 318 | 24 |
| 1998-06-17 | vs SEA | 69 | W 4-2 | 41-28 | 1 | 24,800 | Omar Olivares | Jeff Fassero | Omar Olivares | Jeff Fassero | Troy Percival | 346 | 320 | 26 |
| 1998-06-18 | vs SEA | 70 | W 11-5 | 42-28 | 1 | 30,268 | Jarrod Washburn | Jamie Moyer | Jarrod Washburn | Paul Spoljaric | Rich DeLucia | 357 | 325 | 32 |
| 1998-06-19 | vs TEX | 71 | L 3-7 | 42-29 | 1 | 38,866 | Chuck Finley | Rick Helling | Rick Helling | Chuck Finley | | 360 | 332 | 28 |
| 1998-06-20 | vs TEX | 72 | W 8-3 | 43-29 | 1 | 31,671 | Steve Sparks | Todd Van Poppel | Steve Sparks | Todd Van Poppel | | 368 | 335 | 33 |
| 1998-06-21 | vs TEX | 73 | W 10-7 | 44-29 | 1 | 32,914 | Jason Dickson | Matt Perisho | Jason Dickson | Matt Perisho | Troy Percival | 378 | 342 | 36 |
| 1998-06-22 | vs LAN | 74 | W 6-5 | 45-29 | 1 | 43,491 | Omar Olivares | Ismael Valdez | Troy Percival | Greg McMichael | | 384 | 347 | 37 |
| 1998-06-23 | vs LAN | 75 | W 6-4 | 46-29 | 1 | 43,719 | Jarrod Washburn | Dave Mlicki | Pep Harris | Will Brunson | Rich DeLucia | 390 | 351 | 39 |
| 1998-06-24 | @ LAN | 76 | L 5-6 | 46-30 | 1 | 46,822 | Chuck Finley | Darren Dreifort | Antonio Osuna | Greg Cadaret | | 395 | 357 | 38 |
| 1998-06-25 | @ LAN | 77 | W 3-2 | 47-30 | 1 | 38,254 | Steve Sparks | Dennys Reyes | Steve Sparks | Dennys Reyes | Troy Percival | 398 | 359 | 39 |
| 1998-06-26 | @ SDN | 78 | L 3-6 | 47-31 | 1 | 40,621 | Jason Dickson | Kevin Brown | Kevin Brown | Jason Dickson | Trevor Hoffman | 401 | 365 | 36 |
| 1998-06-27 | @ SDN | 79 | L 1-5 | 47-32 | 1 | 31,948 | Omar Olivares | Sterling Hitchcock | Sterling Hitchcock | Omar Olivares | | 402 | 370 | 32 |
| 1998-06-28 | @ SDN | 80 | W 11-3 | 48-32 | 1 | 41,547 | Jarrod Washburn | Joey Hamilton | Jarrod Washburn | Joey Hamilton | | 413 | 373 | 40 |
| 1998-06-30 | vs SFN | 81 | W 4-3 | 49-32 | 1 | 25,629 | Chuck Finley | Shawn Estes | Chuck Finley | Shawn Estes | Troy Percival | 417 | 376 | 41 |
| 1998-07-01 | vs SFN | 82 | L 3-6 | 49-33 | 1 | 24,299 | Steve Sparks | Danny Darwin | Robb Nen | Greg Cadaret | | 420 | 382 | 38 |
| 1998-07-02 | vs SFN | 83 | L 4-7 | 49-34 | 1 | 33,272 | Jason Dickson | Kirk Rueter | Kirk Rueter | Jason Dickson | | 424 | 389 | 35 |
| 1998-07-03 | vs OAK | 84 | L 6-10 | 49-35 | 1 | 39,636 | Omar Olivares | Tom Candiotti | Tom Candiotti | Omar Olivares | | 430 | 399 | 31 |
| 1998-07-04 | vs OAK | 85 | L 3-8 | 49-36 | 1 | 43,571 | Jarrod Washburn | Mike Oquist | Mike Oquist | Jarrod Washburn | Billy Taylor | 433 | 407 | 26 |
| 1998-07-05 | vs OAK | 86 | L 4-5 | 49-37 | 1 | 23,208 | Chuck Finley | Jimmy Haynes | Mike Fetters | Troy Percival | Billy Taylor | 437 | 412 | 25 |
| 1998-07-09 | @ SEA | 87 | L 6-8 | 49-38 | 1 | 24,210 | Omar Olivares | Jeff Fassero | Jeff Fassero | Omar Olivares | Mike Timlin | 443 | 420 | 23 |
| 1998-07-10 | @ SEA | 88 | W 5-3 | 50-38 | 1 | 28,689 | Chuck Finley | Jamie Moyer | Troy Percival | Bobby Ayala | | 448 | 423 | 25 |
| 1998-07-11 | @ SEA | 89 | L 0-2 | 50-39 | 2 | 35,788 | Steve Sparks | Randy Johnson | Randy Johnson | Steve Sparks | | 448 | 425 | 23 |
| 1998-07-12 | @ SEA | 90 | W 8-5 | 51-39 | 1 | 32,797 | Jason Dickson | Bill Swift | Jason Dickson | Bill Swift | Troy Percival | 456 | 430 | 26 |
| 1998-07-13 | @ OAK | 91 | L 2-5 | 51-40 | 1 | 8,401 | Jarrod Washburn | Mike Oquist | Mike Oquist | Jarrod Washburn | Billy Taylor | 458 | 435 | 23 |
| 1998-07-14 | @ OAK | 92 | L 2-6 | 51-41 | 1 | 10,231 | Omar Olivares | Kenny Rogers | Kenny Rogers | Omar Olivares | | 460 | 441 | 19 |
| 1998-07-15 | vs TBA | 93 | W 4-2 | 52-41 | 1 | 19,681 | Chuck Finley | Wilson Alvarez | Shigetoshi Hasegawa | Wilson Alvarez | Troy Percival | 464 | 443 | 21 |
| 1998-07-16 | vs TBA | 94 | L 1-8 | 52-42 | 1 | 24,085 | Steve Sparks | Rolando Arrojo | Rolando Arrojo | Steve Sparks | | 465 | 451 | 14 |
| 1998-07-17 | vs BAL | 95 | L 1-4 | 52-43 | 1 | 34,618 | Jason Dickson | Doug Drabek | Doug Drabek | Jason Dickson | Armando Benitez | 466 | 455 | 11 |
| 1998-07-18 | vs BAL | 96 | W 8-3 | 53-43 | 1 | 37,806 | Jarrod Washburn | Nerio Rodriguez | Jarrod Washburn | Nerio Rodriguez | | 474 | 458 | 16 |
| 1998-07-19 | vs BAL | 97 | L 4-7 | 53-44 | 2 | 38,840 | Omar Olivares | Mike Mussina | Jesse Orosco | Troy Percival | | 478 | 465 | 13 |
| 1998-07-21 | @ MIN | 98 | L 2-4 | 53-45 | 2 | 11,869 | Allen Watson | LaTroy Hawkins | LaTroy Hawkins | Allen Watson | Rick Aguilera | 480 | 469 | 11 |
| 1998-07-22 | @ MIN | 99 | W 5-3 | 54-45 | 2 | 10,484 | Steve Sparks | Brad Radke | Shigetoshi Hasegawa | Greg Swindell | Troy Percival | 485 | 472 | 13 |
| 1998-07-23 | @ MIN | 100 | W 6-5 | 55-45 | 2 | 18,059 | Jason Dickson | Eric Milton | Pep Harris | Hector Carrasco | Troy Percival | 491 | 477 | 14 |
| 1998-07-24 | @ KCA | 101 | L 3-4 | 55-46 | 2 | 18,151 | Chuck Finley | Hipolito Pichardo | Hipolito Pichardo | Chuck Finley | Jeff Montgomery | 494 | 481 | 13 |
| 1998-07-25 | @ KCA | 102 | W 6-5 | 56-46 | 1 | 28,428 | Jarrod Washburn | Tim Belcher | Pep Harris | Tim Belcher | Mike Holtz | 500 | 486 | 14 |
| 1998-07-26 | @ KCA | 103 | L 4-9 | 56-47 | 1 | 20,702 | Omar Olivares | Jose Rosado | Jose Rosado | Omar Olivares | | 504 | 495 | 9 |
| 1998-07-27 | @ KCA | 104 | W 6-1 | 57-47 | 1 | 17,252 | Allen Watson | Pat Rapp | Allen Watson | Pat Rapp | Shigetoshi Hasegawa | 510 | 496 | 14 |
| 1998-07-28 | vs NYA | 105 | L 3-9 | 57-48 | 1 | 36,241 | Jason Dickson | David Cone | David Cone | Jason Dickson | | 513 | 505 | 8 |
| 1998-07-29 | vs NYA | 106 | W 10-5 | 58-48 | 1 | 38,829 | Steve Sparks | Orlando Hernandez | Steve Sparks | Orlando Hernandez | | 523 | 510 | 13 |
| 1998-07-30 | vs NYA | 107 | L 0-3 | 58-49 | 1 | 42,915 | Chuck Finley | Andy Pettitte | Ramiro Mendoza | Rich DeLucia | Mariano Rivera | 523 | 513 | 10 |
| 1998-07-31 | vs BOS | 108 | L 2-7 | 58-50 | 1 | 43,390 | Omar Olivares | Bret Saberhagen | Bret Saberhagen | Omar Olivares | Tom Gordon | 525 | 520 | 5 |
| 1998-08-01 | vs BOS | 109 | L 3-11 | 58-51 | 1 | 29,893 | Allen Watson | Pedro Martinez | Pedro Martinez | Allen Watson | Derek Lowe | 528 | 531 | -3 |
| 1998-08-02 | vs BOS | 110 | L 7-8 | 58-52 | 2 | 35,763 | Jason Dickson | Tim Wakefield | Tim Wakefield | Jason Dickson | Tom Gordon | 535 | 539 | -4 |
| 1998-08-03 | vs CLE | 111 | W 11-4 | 59-52 | 2 | 25,339 | Steve Sparks | Jaret Wright | Steve Sparks | Jaret Wright | | 546 | 543 | 3 |
| 1998-08-04 | vs CLE | 112 | W 5-4 | 60-52 | 2 | 29,916 | Chuck Finley | Dave Burba | Shigetoshi Hasegawa | Doug Jones | Troy Percival | 551 | 547 | 4 |
| 1998-08-05 | vs CLE | 113 | L 5-6 | 60-53 | 2 | 43,104 | Omar Olivares | Bartolo Colon | Paul Shuey | Troy Percival | Paul Assenmacher | 556 | 553 | 3 |
| 1998-08-08 | @ CHA | 114 | L 5-7 | 60-55 | 2 | 0 | Jason Dickson | Mike Sirotka | Mike Sirotka | Jason Dickson | Bill Simas | 561 | 560 | 1 |
| 1998-08-08 | @ CHA | 115 | L 3-4 | 60-55 | 2 | 24,073 | Steve Sparks | Jaime Navarro | Chad Bradford | Shigetoshi Hasegawa | | 564 | 564 | 0 |
| 1998-08-09 | @ CHA | 116 | W 9-0 | 61-55 | 2 | 16,805 | Chuck Finley | James Baldwin | Chuck Finley | James Baldwin | | 573 | 564 | 9 |
| 1998-08-10 | @ DET | 117 | W 6-2 | 62-55 | 2 | 15,928 | Omar Olivares | Frank Castillo | Omar Olivares | Frank Castillo | | 579 | 566 | 13 |
| 1998-08-11 | @ DET | 118 | W 5-4 | 63-55 | 2 | 13,010 | Jeff Juden | Brian Moehler | Mike Fetters | Sean Runyan | Troy Percival | 584 | 570 | 14 |
| 1998-08-12 | @ DET | 119 | W 3-2 | 64-55 | 2 | 12,485 | Steve Sparks | Seth Greisinger | Steve Sparks | Seth Greisinger | Troy Percival | 587 | 572 | 15 |
| 1998-08-13 | @ TOR | 120 | L 3-4 | 64-56 | 2 | 26,481 | Chuck Finley | Woody Williams | Bill Risley | Shigetoshi Hasegawa | Dan Plesac | 590 | 576 | 14 |
| 1998-08-14 | @ TOR | 121 | W 7-5 | 65-56 | 1 | 27,276 | Allen Watson | Pat Hentgen | Allen Watson | Pat Hentgen | Troy Percival | 597 | 581 | 16 |
| 1998-08-15 | @ TOR | 122 | W 6-3 | 66-56 | 1 | 30,379 | Omar Olivares | Roger Clemens | Rich DeLucia | Steve Sinclair | | 603 | 584 | 19 |
| 1998-08-16 | @ TOR | 123 | L 4-6 | 66-57 | 1 | 29,259 | Jeff Juden | Chris Carpenter | Chris Carpenter | Jeff Juden | Paul Quantrill | 607 | 590 | 17 |
| 1998-08-17 | vs CHA | 124 | W 7-2 | 67-57 | 1 | 22,174 | Steve Sparks | Jim Parque | Steve Sparks | Jim Parque | | 614 | 592 | 22 |
| 1998-08-18 | vs CHA | 125 | L 3-4 | 67-58 | 1 | 26,160 | Chuck Finley | John Snyder | John Snyder | Chuck Finley | Bill Simas | 617 | 596 | 21 |
| 1998-08-19 | vs DET | 126 | W 2-0 | 68-58 | 1 | 21,841 | Jack McDowell | Justin Thompson | Jack McDowell | Justin Thompson | Troy Percival | 619 | 596 | 23 |
| 1998-08-20 | vs DET | 127 | W 13-2 | 69-58 | 1 | 27,548 | Omar Olivares | Brian Powell | Omar Olivares | Brian Powell | | 632 | 598 | 34 |
| 1998-08-21 | vs TOR | 128 | L 4-9 | 69-59 | 1 | 36,052 | Jeff Juden | Chris Carpenter | Chris Carpenter | Jeff Juden | | 636 | 607 | 29 |
| 1998-08-22 | vs TOR | 129 | W 5-1 | 70-59 | 1 | 42,882 | Steve Sparks | Kelvim Escobar | Steve Sparks | Kelvim Escobar | Shigetoshi Hasegawa | 641 | 608 | 33 |
| 1998-08-23 | vs TOR | 130 | W 3-2 | 71-59 | 1 | 34,142 | Chuck Finley | Woody Williams | Chuck Finley | Carlos Almanzar | Troy Percival | 644 | 610 | 34 |
| 1998-08-24 | @ NYA | 131 | W 7-3 | 72-59 | 1 | 19,297 | Jack McDowell | Andy Pettitte | Jack McDowell | Andy Pettitte | | 651 | 613 | 38 |
| 1998-08-25 | @ NYA | 132 | W 7-6 | 73-59 | 1 | 30,422 | Omar Olivares | Hideki Irabu | Allen Watson | Mike Stanton | Troy Percival | 658 | 619 | 39 |
| 1998-08-26 | @ NYA | 133 | W 6-4 | 74-60 | 1 | 20,077 | Jeff Juden | Ryan Bradley | Jeff Juden | Ryan Bradley | Troy Percival | 664 | 623 | 41 |
| 1998-08-26 | @ NYA | 134 | L 6-7 | 74-60 | 1 | 28,837 | Steve Sparks | David Wells | Mariano Rivera | Mike Fetters | | 670 | 630 | 40 |
| 1998-08-27 | @ NYA | 135 | L 5-6 | 74-61 | 1 | 29,213 | Chuck Finley | David Cone | Jay Tessmer | Mike Fetters | | 675 | 636 | 39 |
| 1998-08-28 | @ BOS | 136 | W 7-6 | 75-61 | 1 | 32,470 | Ken Hill | Steve Avery | Ken Hill | Steve Avery | | 682 | 642 | 40 |
| 1998-08-29 | @ BOS | 137 | L 1-6 | 75-62 | 1 | 32,519 | Jack McDowell | Pedro Martinez | Pedro Martinez | Jack McDowell | | 683 | 648 | 35 |
| 1998-08-30 | @ BOS | 138 | W 8-6 | 76-62 | 1 | 31,476 | Jeff Juden | Tim Wakefield | Shigetoshi Hasegawa | Tim Wakefield | Troy Percival | 691 | 654 | 37 |
| 1998-09-01 | @ CLE | 139 | L 6-7 | 76-63 | 1 | 43,184 | Chuck Finley | Jaret Wright | Steve Reed | Rich DeLucia | | 697 | 661 | 36 |
| 1998-09-02 | @ CLE | 140 | W 13-5 | 77-63 | 1 | 43,200 | Steve Sparks | Bartolo Colon | Steve Sparks | Bartolo Colon | | 710 | 666 | 44 |
| 1998-09-04 | vs KCA | 141 | L 3-5 | 77-64 | 1 | 33,832 | Ken Hill | Pat Rapp | Ricky Bones | Mike Holtz | Jeff Montgomery | 713 | 671 | 42 |
| 1998-09-05 | vs KCA | 142 | W 2-1 | 78-64 | 1 | 37,217 | Jack McDowell | Brian Barber | Jack McDowell | Brian Barber | Rich DeLucia | 715 | 672 | 43 |
| 1998-09-06 | vs KCA | 143 | W 3-0 | 79-64 | 1 | 33,941 | Chuck Finley | Tim Belcher | Chuck Finley | Tim Belcher | Shigetoshi Hasegawa | 718 | 672 | 46 |
| 1998-09-08 | vs MIN | 144 | L 0-5 | 79-65 | 1 | 20,444 | Steve Sparks | Brad Radke | Brad Radke | Steve Sparks | | 718 | 677 | 41 |
| 1998-09-09 | vs MIN | 145 | W 10-8 | 80-65 | 1 | 20,070 | Ken Hill | Frankie Rodriguez | Omar Olivares | Frankie Rodriguez | Troy Percival | 728 | 685 | 43 |
| 1998-09-11 | @ BAL | 146 | L 3-8 | 80-66 | 1 | 46,832 | Chuck Finley | Scott Erickson | Scott Erickson | Chuck Finley | | 731 | 693 | 38 |
| 1998-09-12 | @ BAL | 147 | L 2-3 | 80-67 | 1 | 48,038 | Steve Sparks | Mike Mussina | Alan Mills | Troy Percival | | 733 | 696 | 37 |
| 1998-09-13 | @ BAL | 148 | L 7-12 | 80-68 | 1 | 48,013 | Jack McDowell | Rocky Coppinger | Jimmy Key | Jarrod Washburn | | 740 | 708 | 32 |
| 1998-09-14 | @ TBA | 149 | W 4-2 | 81-68 | 1 | 24,279 | Omar Olivares | Wilson Alvarez | Shigetoshi Hasegawa | Albie Lopez | Troy Percival | 744 | 710 | 34 |
| 1998-09-15 | @ TBA | 150 | L 1-8 | 81-69 | 1 | 24,347 | Jeff Juden | Rolando Arrojo | Rolando Arrojo | Jeff Juden | | 745 | 718 | 27 |
| 1998-09-16 | @ TEX | 151 | L 3-5 | 81-70 | 1 | 37,481 | Chuck Finley | Todd Stottlemyre | Todd Stottlemyre | Chuck Finley | | 748 | 723 | 25 |
| 1998-09-17 | @ TEX | 152 | L 6-7 | 81-71 | 2 | 45,928 | Steve Sparks | Rick Helling | Tim Crabtree | Pep Harris | John Wetteland | 754 | 730 | 24 |
| 1998-09-18 | vs SEA | 153 | L 3-5 | 81-72 | 2 | 39,902 | Ken Hill | Ken Cloude | Mike Timlin | Rich DeLucia | | 757 | 735 | 22 |
| 1998-09-19 | vs SEA | 154 | W 5-3 | 82-72 | 2 | 42,833 | Jack McDowell | Mac Suzuki | Jack McDowell | Paul Spoljaric | Troy Percival | 762 | 738 | 24 |
| 1998-09-20 | vs SEA | 155 | W 3-1 | 83-72 | 1 | 42,972 | Omar Olivares | Paul Abbott | Omar Olivares | Paul Abbott | Troy Percival | 765 | 739 | 26 |
| 1998-09-21 | vs TEX | 156 | L 1-9 | 83-73 | 2 | 33,487 | Steve Sparks | Todd Stottlemyre | Todd Stottlemyre | Steve Sparks | | 766 | 748 | 18 |
| 1998-09-22 | vs TEX | 157 | L 1-9 | 83-74 | 2 | 38,987 | Chuck Finley | Rick Helling | Rick Helling | Chuck Finley | | 767 | 757 | 10 |
| 1998-09-23 | vs TEX | 158 | L 1-7 | 83-75 | 2 | 42,776 | Ken Hill | John Burkett | John Burkett | Ken Hill | | 768 | 764 | 4 |
| 1998-09-24 | @ OAK | 159 | W 10-6 | 84-75 | 2 | 9,268 | Jack McDowell | Jimmy Haynes | Jason Dickson | Jimmy Haynes | | 778 | 770 | 8 |
| 1998-09-25 | @ OAK | 160 | L 2-7 | 84-76 | 2 | 22,861 | Omar Olivares | Kenny Rogers | Kenny Rogers | Omar Olivares | | 780 | 777 | 3 |
| 1998-09-26 | @ OAK | 161 | L 3-4 | 84-77 | 2 | 22,661 | Steve Sparks | Gil Heredia | T.J. Mathews | Troy Percival | | 783 | 781 | 2 |
| 1998-09-27 | @ OAK | 162 | W 4-2 | 85-77 | 2 | 22,819 | Jarrod Washburn | Jay Witasick | Jarrod Washburn | Jay Witasick | Shigetoshi Hasegawa | 787 | 783 | 4 |