| 1998-03-31 | vs CHA | 1 | L 2-9 | 0-1 | 4 | 45,909 | John Burkett | Jaime Navarro | Jaime Navarro | John Burkett | | 2 | 9 | -7 |
| 1998-04-02 | vs CHA | 2 | W 20-4 | 1-1 | 2 | 32,663 | Aaron Sele | Mike Sirotka | Aaron Sele | Mike Sirotka | Roger Pavlik | 22 | 13 | 9 |
| 1998-04-03 | @ TOR | 3 | W 5-0 | 2-1 | 2 | 25,509 | Rick Helling | Juan Guzman | Rick Helling | Juan Guzman | | 27 | 13 | 14 |
| 1998-04-04 | @ TOR | 4 | L 2-9 | 2-2 | 3 | 30,156 | Darren Oliver | Woody Williams | Woody Williams | Darren Oliver | | 29 | 22 | 7 |
| 1998-04-05 | @ TOR | 5 | W 6-5 | 3-2 | 1 | 28,106 | John Burkett | Chris Carpenter | John Burkett | Bill Risley | John Wetteland | 35 | 27 | 8 |
| 1998-04-06 | @ CHA | 6 | L 4-5 | 3-3 | 3 | 25,358 | Bobby Witt | Jaime Navarro | Keith Foulke | Roger Pavlik | Matt Karchner | 39 | 32 | 7 |
| 1998-04-09 | @ CHA | 7 | W 11-0 | 4-3 | 2 | 10,654 | Aaron Sele | James Baldwin | Aaron Sele | James Baldwin | | 50 | 32 | 18 |
| 1998-04-10 | vs TOR | 8 | W 4-3 | 5-3 | 1 | 32,314 | Rick Helling | Woody Williams | Rick Helling | Dan Plesac | John Wetteland | 54 | 35 | 19 |
| 1998-04-11 | vs TOR | 9 | L 8-9 | 5-4 | 1 | 37,520 | Darren Oliver | Chris Carpenter | Carlos Almanzar | Darren Oliver | Randy Myers | 62 | 44 | 18 |
| 1998-04-12 | vs TOR | 10 | W 3-1 | 6-4 | 1 | 28,435 | John Burkett | Erik Hanson | John Wetteland | Paul Quantrill | | 65 | 45 | 20 |
| 1998-04-13 | vs DET | 11 | W 10-1 | 7-4 | 1 | 28,671 | Bobby Witt | Brian Moehler | Bobby Witt | Brian Moehler | | 75 | 46 | 29 |
| 1998-04-14 | vs DET | 12 | W 11-2 | 8-4 | 1 | 24,409 | Aaron Sele | Scott Sanders | Aaron Sele | Scott Sanders | | 86 | 48 | 38 |
| 1998-04-15 | vs DET | 13 | W 7-3 | 9-4 | 1 | 24,085 | Rick Helling | Tim Worrell | Rick Helling | Tim Worrell | | 93 | 51 | 42 |
| 1998-04-17 | vs BAL | 14 | W 6-4 | 10-4 | 1 | 37,415 | Darren Oliver | Scott Erickson | Roger Pavlik | Scott Erickson | John Wetteland | 99 | 55 | 44 |
| 1998-04-18 | vs BAL | 15 | L 8-10 | 10-5 | 1 | 43,883 | John Burkett | Scott Kamieniecki | Scott Kamieniecki | John Burkett | | 107 | 65 | 42 |
| 1998-04-19 | vs BAL | 16 | W 11-7 | 11-5 | 1 | 43,037 | Bobby Witt | Jimmy Key | Bobby Witt | Jimmy Key | John Wetteland | 118 | 72 | 46 |
| 1998-04-21 | vs TBA | 17 | W 4-0 | 12-5 | 1 | 26,776 | Aaron Sele | Dennis Springer | Aaron Sele | Dennis Springer | | 122 | 72 | 50 |
| 1998-04-22 | vs TBA | 18 | W 7-2 | 13-5 | 1 | 30,770 | Rick Helling | Tony Saunders | Rick Helling | Tony Saunders | | 129 | 74 | 55 |
| 1998-04-23 | vs TBA | 19 | L 5-12 | 13-6 | 1 | 33,319 | Darren Oliver | Jason Johnson | Jason Johnson | Darren Oliver | | 134 | 86 | 48 |
| 1998-04-24 | @ KCA | 20 | L 4-11 | 13-7 | 1 | 17,718 | John Burkett | Glendon Rusch | Glendon Rusch | John Burkett | | 138 | 97 | 41 |
| 1998-04-25 | @ KCA | 21 | W 11-8 | 14-7 | 1 | 24,453 | Bobby Witt | Pat Rapp | Bobby Witt | Pat Rapp | John Wetteland | 149 | 105 | 44 |
| 1998-04-26 | @ KCA | 22 | W 11-4 | 15-7 | 1 | 15,768 | Aaron Sele | Chris Haney | Aaron Sele | Chris Haney | | 160 | 109 | 51 |
| 1998-04-27 | @ MIN | 23 | W 9-4 | 16-7 | 1 | 8,349 | Rick Helling | Mike Morgan | Rick Helling | Mike Morgan | | 169 | 113 | 56 |
| 1998-04-28 | @ MIN | 24 | W 7-2 | 17-7 | 1 | 8,570 | Darren Oliver | Eric Milton | Darren Oliver | Eric Milton | | 176 | 115 | 61 |
| 1998-04-29 | @ DET | 25 | W 4-1 | 18-7 | 1 | 10,051 | John Burkett | Greg Keagle | John Burkett | Greg Keagle | John Wetteland | 180 | 116 | 64 |
| 1998-04-30 | @ DET | 26 | L 2-7 | 18-8 | 1 | 29,336 | Bobby Witt | Brian Moehler | Brian Moehler | Bobby Witt | | 182 | 123 | 59 |
| 1998-05-01 | @ BOS | 27 | L 3-5 | 18-9 | 1 | 24,169 | Aaron Sele | Bret Saberhagen | John Wasdin | Aaron Sele | Tom Gordon | 185 | 128 | 57 |
| 1998-05-02 | @ BOS | 28 | W 7-6 | 19-9 | 1 | 25,827 | Rick Helling | Brian Rose | Rick Helling | Brian Rose | John Wetteland | 192 | 134 | 58 |
| 1998-05-03 | @ BOS | 29 | L 1-2 | 19-10 | 1 | 28,075 | Darren Oliver | Pedro Martinez | Pedro Martinez | Darren Oliver | Tom Gordon | 193 | 136 | 57 |
| 1998-05-05 | vs NYA | 30 | L 2-7 | 19-11 | 1 | 31,693 | John Burkett | David Cone | David Cone | John Burkett | | 195 | 143 | 52 |
| 1998-05-06 | vs NYA | 31 | L 13-15 | 19-12 | 1 | 33,274 | Bobby Witt | David Wells | Mike Stanton | Danny Patterson | Mariano Rivera | 208 | 158 | 50 |
| 1998-05-07 | vs CLE | 32 | L 2-7 | 19-13 | 1 | 28,504 | Aaron Sele | Bartolo Colon | Bartolo Colon | Aaron Sele | | 210 | 165 | 45 |
| 1998-05-08 | vs CLE | 33 | W 6-3 | 20-13 | 1 | 38,067 | Rick Helling | Chad Ogea | Xavier Hernandez | Jose Mesa | John Wetteland | 216 | 168 | 48 |
| 1998-05-09 | vs CLE | 34 | W 7-3 | 21-13 | 1 | 46,355 | Darren Oliver | Charles Nagy | Darren Oliver | Charles Nagy | | 223 | 171 | 52 |
| 1998-05-10 | vs CLE | 35 | W 5-3 | 22-13 | 1 | 31,232 | John Burkett | Jaret Wright | John Burkett | Jaret Wright | John Wetteland | 228 | 174 | 54 |
| 1998-05-11 | vs BOS | 36 | W 8-2 | 23-13 | 1 | 40,275 | Bobby Witt | John Wasdin | Bobby Witt | John Wasdin | | 236 | 176 | 60 |
| 1998-05-12 | vs BOS | 37 | W 6-3 | 24-13 | 1 | 39,614 | Aaron Sele | Brian Rose | Aaron Sele | Brian Rose | John Wetteland | 242 | 179 | 63 |
| 1998-05-13 | @ NYA | 38 | L 6-8 | 24-14 | 1 | 23,142 | Rick Helling | David Cone | David Cone | Rick Helling | Mariano Rivera | 248 | 187 | 61 |
| 1998-05-14 | @ NYA | 39 | W 7-5 | 25-14 | 1 | 20,694 | Darren Oliver | Hideki Irabu | Danny Patterson | Willie Banks | John Wetteland | 255 | 192 | 63 |
| 1998-05-15 | @ CLE | 40 | L 2-3 | 25-15 | 1 | 41,128 | John Burkett | Jaret Wright | Rick Krivda | Al Levine | | 257 | 195 | 62 |
| 1998-05-16 | @ CLE | 41 | L 3-10 | 25-16 | 1 | 40,925 | Bobby Witt | Dave Burba | Dave Burba | Bobby Witt | | 260 | 205 | 55 |
| 1998-05-17 | @ CLE | 42 | W 1-0 | 26-16 | 1 | 42,247 | Aaron Sele | Bartolo Colon | Aaron Sele | Bartolo Colon | John Wetteland | 261 | 205 | 56 |
| 1998-05-19 | vs SEA | 43 | W 10-4 | 27-16 | 1 | 37,258 | Rick Helling | Randy Johnson | Rick Helling | Randy Johnson | Xavier Hernandez | 271 | 209 | 62 |
| 1998-05-20 | vs SEA | 44 | W 8-7 | 28-16 | 1 | 29,454 | Darren Oliver | Bill Swift | Tim Crabtree | Mike Timlin | John Wetteland | 279 | 216 | 63 |
| 1998-05-21 | vs SEA | 45 | W 9-8 | 29-16 | 1 | 34,613 | John Burkett | Jeff Fassero | Scott Bailes | Bobby Ayala | | 288 | 224 | 64 |
| 1998-05-22 | vs KCA | 46 | W 13-10 | 30-16 | 1 | 38,411 | Bobby Witt | Jamie Walker | John Wetteland | Jeff Montgomery | | 301 | 234 | 67 |
| 1998-05-23 | vs KCA | 47 | W 7-3 | 31-16 | 1 | 46,372 | Aaron Sele | Glendon Rusch | Aaron Sele | Glendon Rusch | | 308 | 237 | 71 |
| 1998-05-24 | vs KCA | 48 | L 3-8 | 31-17 | 1 | 46,243 | Rick Helling | Pat Rapp | Pat Rapp | Rick Helling | Hipolito Pichardo | 311 | 245 | 66 |
| 1998-05-25 | vs MIN | 49 | L 3-9 | 31-18 | 1 | 30,887 | Darren Oliver | Mike Morgan | Mike Morgan | Darren Oliver | | 314 | 254 | 60 |
| 1998-05-27 | vs MIN | 50 | L 5-6 | 31-19 | 1 | 32,657 | John Burkett | Eric Milton | Mike Trombley | Xavier Hernandez | Rick Aguilera | 319 | 260 | 59 |
| 1998-05-28 | @ BAL | 51 | L 2-5 | 31-20 | 1 | 42,294 | Bobby Witt | Doug Drabek | Doug Drabek | Bobby Witt | Jesse Orosco | 321 | 265 | 56 |
| 1998-05-29 | @ BAL | 52 | L 3-6 | 31-21 | 1 | 47,091 | Aaron Sele | Doug Johns | Doug Johns | Aaron Sele | Armando Benitez | 324 | 271 | 53 |
| 1998-05-30 | @ BAL | 53 | W 10-8 | 32-21 | 1 | 47,866 | Rick Helling | Bobby Munoz | Xavier Hernandez | Sidney Ponson | John Wetteland | 334 | 279 | 55 |
| 1998-05-31 | @ BAL | 54 | W 9-5 | 33-21 | 1 | 47,437 | Darren Oliver | Scott Erickson | Darren Oliver | Scott Erickson | Danny Patterson | 343 | 284 | 59 |
| 1998-06-01 | @ TBA | 55 | L 1-4 | 33-22 | 1 | 24,388 | John Burkett | Rolando Arrojo | Rolando Arrojo | John Burkett | Roberto Hernandez | 344 | 288 | 56 |
| 1998-06-02 | @ TBA | 56 | W 7-3 | 34-22 | 1 | 24,477 | Bobby Witt | Jason Johnson | Bobby Witt | Jason Johnson | | 351 | 291 | 60 |
| 1998-06-03 | @ OAK | 57 | W 16-10 | 35-22 | 1 | 5,973 | Aaron Sele | Blake Stein | Tim Crabtree | Blake Stein | | 367 | 301 | 66 |
| 1998-06-04 | @ OAK | 58 | L 1-6 | 35-23 | 1 | 11,039 | Rick Helling | Jimmy Haynes | Jimmy Haynes | Rick Helling | Billy Taylor | 368 | 307 | 61 |
| 1998-06-05 | vs SDN | 59 | W 8-7 | 36-23 | 1 | 37,903 | Darren Oliver | Kevin Brown | Tim Crabtree | Donne Wall | John Wetteland | 376 | 314 | 62 |
| 1998-06-06 | vs SDN | 60 | W 3-0 | 37-23 | 1 | 46,022 | John Burkett | Sterling Hitchcock | John Burkett | Sterling Hitchcock | John Wetteland | 379 | 314 | 65 |
| 1998-06-07 | vs SDN | 61 | L 8-17 | 37-24 | 1 | 46,372 | Bobby Witt | Mark Langston | Dan Miceli | Danny Patterson | | 387 | 331 | 56 |
| 1998-06-08 | @ COL | 62 | W 3-1 | 38-24 | 1 | 48,070 | Aaron Sele | Pedro Astacio | Aaron Sele | Pedro Astacio | John Wetteland | 390 | 332 | 58 |
| 1998-06-09 | @ COL | 63 | W 5-2 | 39-24 | 1 | 48,068 | Rick Helling | John Thomson | Rick Helling | John Thomson | John Wetteland | 395 | 334 | 61 |
| 1998-06-10 | @ COL | 64 | L 8-9 | 39-25 | 1 | 48,061 | Darren Oliver | Bobby Jones | Jerry DiPoto | Eric Gunderson | | 403 | 343 | 60 |
| 1998-06-12 | vs ANA | 65 | L 1-5 | 39-26 | 1 | 35,505 | John Burkett | Omar Olivares | Omar Olivares | John Burkett | Greg Cadaret | 404 | 348 | 56 |
| 1998-06-13 | vs ANA | 66 | L 6-18 | 39-27 | 1 | 46,289 | Aaron Sele | Jarrod Washburn | Jarrod Washburn | Aaron Sele | | 410 | 366 | 44 |
| 1998-06-14 | vs ANA | 67 | W 4-2 | 40-27 | 1 | 36,648 | Rick Helling | Chuck Finley | Rick Helling | Chuck Finley | John Wetteland | 414 | 368 | 46 |
| 1998-06-15 | vs ANA | 68 | L 5-8 | 40-28 | 1 | 43,380 | Bobby Witt | Steve Sparks | Steve Sparks | Bobby Witt | Troy Percival | 419 | 376 | 43 |
| 1998-06-16 | vs OAK | 69 | L 7-9 | 40-29 | 2 | 34,066 | Matt Perisho | Mike Oquist | Buddy Groom | Matt Perisho | Billy Taylor | 426 | 385 | 41 |
| 1998-06-17 | vs OAK | 70 | L 2-3 | 40-30 | 2 | 31,052 | John Burkett | Kenny Rogers | Kenny Rogers | John Burkett | Billy Taylor | 428 | 388 | 40 |
| 1998-06-18 | vs OAK | 71 | W 3-2 | 41-30 | 2 | 35,930 | Aaron Sele | Tom Candiotti | Aaron Sele | Tom Candiotti | John Wetteland | 431 | 390 | 41 |
| 1998-06-19 | @ ANA | 72 | W 7-3 | 42-30 | 2 | 38,866 | Rick Helling | Chuck Finley | Rick Helling | Chuck Finley | | 438 | 393 | 45 |
| 1998-06-20 | @ ANA | 73 | L 3-8 | 42-31 | 2 | 31,671 | Todd Van Poppel | Steve Sparks | Steve Sparks | Todd Van Poppel | | 441 | 401 | 40 |
| 1998-06-21 | @ ANA | 74 | L 7-10 | 42-32 | 2 | 32,914 | Matt Perisho | Jason Dickson | Jason Dickson | Matt Perisho | Troy Percival | 448 | 411 | 37 |
| 1998-06-22 | vs ARI | 75 | L 0-6 | 42-33 | 2 | 37,840 | John Burkett | Andy Benes | Andy Benes | John Burkett | | 448 | 417 | 31 |
| 1998-06-23 | vs ARI | 76 | W 16-5 | 43-33 | 2 | 31,904 | Aaron Sele | Brian Anderson | Aaron Sele | Brian Anderson | | 464 | 422 | 42 |
| 1998-06-24 | @ ARI | 77 | W 3-2 | 44-33 | 2 | 44,296 | Rick Helling | Willie Blair | Rick Helling | Willie Blair | John Wetteland | 467 | 424 | 43 |
| 1998-06-25 | @ ARI | 78 | W 9-4 | 45-33 | 2 | 44,269 | Todd Van Poppel | Amaury Telemaco | Todd Van Poppel | Amaury Telemaco | | 476 | 428 | 48 |
| 1998-06-26 | @ SFN | 79 | W 7-3 | 46-33 | 2 | 18,180 | Darren Oliver | Orel Hershiser | Darren Oliver | Orel Hershiser | John Wetteland | 483 | 431 | 52 |
| 1998-06-27 | @ SFN | 80 | L 5-6 | 46-34 | 2 | 28,753 | John Burkett | Kirk Rueter | Robb Nen | Danny Patterson | | 488 | 437 | 51 |
| 1998-06-28 | @ SFN | 81 | L 0-7 | 46-35 | 2 | 36,664 | Aaron Sele | Mark Gardner | Mark Gardner | Aaron Sele | | 488 | 444 | 44 |
| 1998-06-30 | vs LAN | 82 | L 1-4 | 46-36 | 2 | 37,873 | Rick Helling | Darren Dreifort | Darren Dreifort | Rick Helling | Antonio Osuna | 489 | 448 | 41 |
| 1998-07-01 | vs LAN | 83 | L 5-7 | 46-37 | 2 | 28,928 | Todd Van Poppel | Dennys Reyes | Scott Radinsky | John Wetteland | Antonio Osuna | 494 | 455 | 39 |
| 1998-07-02 | vs LAN | 84 | L 1-4 | 46-38 | 2 | 38,514 | Darren Oliver | Chan Ho Park | Chan Ho Park | Darren Oliver | Scott Radinsky | 495 | 459 | 36 |
| 1998-07-03 | vs SEA | 85 | L 2-8 | 46-39 | 2 | 45,233 | John Burkett | Jeff Fassero | Jeff Fassero | John Burkett | | 497 | 467 | 30 |
| 1998-07-04 | vs SEA | 86 | W 9-2 | 47-39 | 2 | 46,067 | Aaron Sele | Jamie Moyer | Aaron Sele | Jamie Moyer | | 506 | 469 | 37 |
| 1998-07-05 | vs SEA | 87 | W 8-4 | 48-39 | 2 | 38,053 | Rick Helling | Randy Johnson | Xavier Hernandez | Randy Johnson | | 514 | 473 | 41 |
| 1998-07-09 | @ OAK | 88 | W 4-1 | 49-39 | 2 | 11,428 | John Burkett | Kenny Rogers | John Burkett | Billy Taylor | John Wetteland | 518 | 474 | 44 |
| 1998-07-10 | @ OAK | 89 | W 1-0 | 50-39 | 2 | 10,625 | Rick Helling | Tom Candiotti | Rick Helling | Billy Taylor | John Wetteland | 519 | 474 | 45 |
| 1998-07-11 | @ OAK | 90 | W 4-2 | 51-39 | 1 | 26,458 | Aaron Sele | Blake Stein | Xavier Hernandez | Mike Fetters | John Wetteland | 523 | 476 | 47 |
| 1998-07-12 | @ OAK | 91 | L 5-7 | 51-40 | 2 | 22,992 | Darren Oliver | Jimmy Haynes | Jimmy Haynes | Darren Oliver | Billy Taylor | 528 | 483 | 45 |
| 1998-07-13 | @ SEA | 92 | L 3-10 | 51-41 | 2 | 25,170 | Todd Van Poppel | Ken Cloude | Ken Cloude | Todd Van Poppel | | 531 | 493 | 38 |
| 1998-07-14 | @ SEA | 93 | L 3-6 | 51-42 | 2 | 25,545 | John Burkett | Jeff Fassero | Jeff Fassero | John Burkett | Mike Timlin | 534 | 499 | 35 |
| 1998-07-15 | vs BAL | 94 | L 3-14 | 51-43 | 2 | 46,682 | Rick Helling | Sidney Ponson | Sidney Ponson | Rick Helling | | 537 | 513 | 24 |
| 1998-07-16 | vs BAL | 95 | L 3-9 | 51-44 | 2 | 45,171 | Aaron Sele | Scott Erickson | Scott Erickson | Aaron Sele | | 540 | 522 | 18 |
| 1998-07-17 | vs TBA | 96 | W 7-4 | 52-44 | 2 | 33,876 | Darren Oliver | Tony Saunders | Darren Oliver | Jim Mecir | John Wetteland | 547 | 526 | 21 |
| 1998-07-18 | vs TBA | 97 | W 9-8 | 53-44 | 2 | 44,356 | Esteban Loaiza | Julio Santana | Tim Crabtree | Esteban Yan | | 556 | 534 | 22 |
| 1998-07-19 | vs TBA | 98 | W 7-4 | 54-44 | 1 | 34,700 | John Burkett | Bryan Rekar | John Burkett | Bryan Rekar | John Wetteland | 563 | 538 | 25 |
| 1998-07-21 | @ KCA | 99 | W 15-5 | 55-44 | 1 | 17,457 | Rick Helling | Jose Rosado | Rick Helling | Jose Rosado | | 578 | 543 | 35 |
| 1998-07-22 | @ KCA | 100 | L 4-7 | 55-45 | 1 | 14,660 | Aaron Sele | Pat Rapp | Pat Rapp | Aaron Sele | Jeff Montgomery | 582 | 550 | 32 |
| 1998-07-23 | @ KCA | 101 | W 8-4 | 56-45 | 1 | 21,656 | Darren Oliver | Glendon Rusch | Xavier Hernandez | Glendon Rusch | | 590 | 554 | 36 |
| 1998-07-24 | @ MIN | 102 | L 3-5 | 56-46 | 1 | 11,473 | Esteban Loaiza | Dan Serafini | Dan Serafini | Esteban Loaiza | Rick Aguilera | 593 | 559 | 34 |
| 1998-07-25 | @ MIN | 103 | L 6-7 | 56-47 | 2 | 21,013 | John Burkett | Frankie Rodriguez | Greg Swindell | Danny Patterson | Rick Aguilera | 599 | 566 | 33 |
| 1998-07-26 | @ MIN | 104 | L 3-11 | 56-48 | 2 | 13,802 | Rick Helling | LaTroy Hawkins | LaTroy Hawkins | Rick Helling | | 602 | 577 | 25 |
| 1998-07-28 | @ TOR | 105 | L 3-8 | 56-49 | 2 | 29,177 | Aaron Sele | Roger Clemens | Roger Clemens | Aaron Sele | | 605 | 585 | 20 |
| 1998-07-29 | @ TOR | 106 | W 9-6 | 57-49 | 2 | 28,220 | Darren Oliver | Chris Carpenter | Darren Oliver | Chris Carpenter | John Wetteland | 614 | 591 | 23 |
| 1998-07-30 | @ TOR | 107 | L 0-1 | 57-50 | 2 | 29,264 | Esteban Loaiza | Juan Guzman | Juan Guzman | Esteban Loaiza | Randy Myers | 614 | 592 | 22 |
| 1998-07-31 | vs CHA | 108 | L 2-10 | 57-51 | 2 | 38,846 | John Burkett | John Snyder | John Snyder | John Burkett | | 616 | 602 | 14 |
| 1998-08-01 | vs CHA | 109 | W 8-1 | 58-51 | 2 | 42,425 | Rick Helling | Mike Sirotka | Rick Helling | Mike Sirotka | | 624 | 603 | 21 |
| 1998-08-02 | vs CHA | 110 | W 12-3 | 59-51 | 1 | 28,175 | Aaron Sele | Jaime Navarro | Aaron Sele | Jaime Navarro | | 636 | 606 | 30 |
| 1998-08-04 | vs TOR | 111 | W 11-9 | 60-51 | 1 | 45,213 | Todd Stottlemyre | Chris Carpenter | Todd Stottlemyre | Chris Carpenter | John Wetteland | 647 | 615 | 32 |
| 1998-08-05 | vs TOR | 112 | W 4-3 | 61-51 | 1 | 27,766 | Esteban Loaiza | Kelvim Escobar | John Wetteland | Randy Myers | | 651 | 618 | 33 |
| 1998-08-06 | vs BOS | 113 | W 7-4 | 62-51 | 1 | 32,132 | John Burkett | Bret Saberhagen | John Burkett | Bret Saberhagen | John Wetteland | 658 | 622 | 36 |
| 1998-08-07 | vs BOS | 114 | W 4-3 | 63-51 | 1 | 34,906 | Rick Helling | Pedro Martinez | Rick Helling | Pedro Martinez | John Wetteland | 662 | 625 | 37 |
| 1998-08-08 | vs BOS | 115 | L 1-11 | 63-52 | 1 | 44,242 | Aaron Sele | Tim Wakefield | Tim Wakefield | Aaron Sele | | 663 | 636 | 27 |
| 1998-08-09 | vs BOS | 116 | L 8-14 | 63-53 | 1 | 31,127 | Todd Stottlemyre | John Wasdin | Jim Corsi | Todd Stottlemyre | | 671 | 650 | 21 |
| 1998-08-11 | @ CLE | 117 | W 2-1 | 64-53 | 1 | 42,992 | Esteban Loaiza | Steve Karsay | Esteban Loaiza | Steve Karsay | John Wetteland | 673 | 651 | 22 |
| 1998-08-12 | @ CLE | 118 | L 3-6 | 64-54 | 1 | 43,247 | John Burkett | Bartolo Colon | Bartolo Colon | John Burkett | Michael Jackson | 676 | 657 | 19 |
| 1998-08-13 | @ NYA | 119 | L 0-2 | 64-55 | 1 | 53,835 | Rick Helling | Orlando Hernandez | Orlando Hernandez | Rick Helling | Mariano Rivera | 676 | 659 | 17 |
| 1998-08-14 | @ NYA | 120 | L 4-6 | 64-56 | 2 | 46,547 | Aaron Sele | Andy Pettitte | Andy Pettitte | Aaron Sele | Mariano Rivera | 680 | 665 | 15 |
| 1998-08-15 | @ NYA | 121 | W 16-5 | 65-56 | 2 | 53,117 | Todd Stottlemyre | Hideki Irabu | Todd Stottlemyre | Hideki Irabu | | 696 | 670 | 26 |
| 1998-08-16 | @ NYA | 122 | L 5-6 | 65-57 | 2 | 50,304 | Esteban Loaiza | David Wells | Mariano Rivera | Xavier Hernandez | | 701 | 676 | 25 |
| 1998-08-18 | @ BOS | 123 | L 1-4 | 65-59 | 2 | 33,201 | John Burkett | Pedro Martinez | Pedro Martinez | John Burkett | Tom Gordon | 702 | 680 | 22 |
| 1998-08-18 | @ BOS | 124 | L 4-5 | 65-59 | 2 | 26,677 | Rick Helling | Bret Saberhagen | Derek Lowe | Danny Patterson | Tom Gordon | 706 | 685 | 21 |
| 1998-08-19 | vs CLE | 125 | W 3-1 | 66-59 | 2 | 26,146 | Aaron Sele | Charles Nagy | Aaron Sele | Charles Nagy | John Wetteland | 709 | 686 | 23 |
| 1998-08-20 | vs CLE | 126 | W 8-2 | 67-59 | 2 | 37,094 | Todd Stottlemyre | Dave Burba | Todd Stottlemyre | Dave Burba | Danny Patterson | 717 | 688 | 29 |
| 1998-08-21 | vs NYA | 127 | L 0-5 | 67-60 | 2 | 45,841 | Esteban Loaiza | David Wells | David Wells | Esteban Loaiza | | 717 | 693 | 24 |
| 1998-08-22 | vs NYA | 128 | L 9-12 | 67-61 | 2 | 46,483 | John Burkett | David Cone | Ryan Bradley | Xavier Hernandez | Mariano Rivera | 726 | 705 | 21 |
| 1998-08-23 | vs NYA | 129 | W 12-10 | 68-61 | 2 | 37,284 | Rick Helling | Orlando Hernandez | Rick Helling | Orlando Hernandez | John Wetteland | 738 | 715 | 23 |
| 1998-08-24 | vs DET | 130 | W 6-5 | 69-61 | 2 | 24,544 | Aaron Sele | Justin Thompson | Aaron Sele | Justin Thompson | John Wetteland | 744 | 720 | 24 |
| 1998-08-25 | vs DET | 131 | L 7-8 | 69-62 | 2 | 23,378 | Todd Stottlemyre | Brian Powell | Brian Powell | Todd Stottlemyre | | 751 | 728 | 23 |
| 1998-08-26 | vs DET | 132 | W 8-6 | 70-62 | 2 | 22,618 | Esteban Loaiza | Bryce Florie | Esteban Loaiza | Bryce Florie | John Wetteland | 759 | 734 | 25 |
| 1998-08-28 | @ CHA | 133 | W 6-5 | 71-63 | 2 | 0 | Rick Helling | John Snyder | Xavier Hernandez | Bob Howry | John Wetteland | 765 | 739 | 26 |
| 1998-08-28 | @ CHA | 134 | L 7-8 | 71-63 | 2 | 14,280 | John Burkett | Scott Eyre | Bryan Ward | Eric Gunderson | Bob Howry | 772 | 747 | 25 |
| 1998-08-29 | @ CHA | 135 | W 5-3 | 72-63 | 2 | 16,424 | Aaron Sele | Mike Sirotka | Aaron Sele | Mike Sirotka | John Wetteland | 777 | 750 | 27 |
| 1998-08-30 | @ CHA | 136 | L 3-5 | 72-64 | 2 | 16,701 | Todd Stottlemyre | Tom Fordham | Carlos Castillo | Todd Stottlemyre | Bob Howry | 780 | 755 | 25 |
| 1998-08-31 | @ DET | 137 | W 13-2 | 73-64 | 2 | 11,964 | Esteban Loaiza | Bryce Florie | Esteban Loaiza | Bryce Florie | | 793 | 757 | 36 |
| 1998-09-01 | @ DET | 138 | L 8-12 | 73-65 | 2 | 9,733 | John Burkett | Frank Castillo | Matt Anderson | Tim Crabtree | A.J. Sager | 801 | 769 | 32 |
| 1998-09-02 | @ DET | 139 | W 5-3 | 74-65 | 2 | 10,699 | Rick Helling | Brian Moehler | Rick Helling | Brian Moehler | John Wetteland | 806 | 772 | 34 |
| 1998-09-04 | vs MIN | 140 | W 9-3 | 75-65 | 2 | 25,580 | Aaron Sele | Frankie Rodriguez | Aaron Sele | Frankie Rodriguez | | 815 | 775 | 40 |
| 1998-09-05 | vs MIN | 141 | L 4-7 | 75-66 | 2 | 38,581 | Todd Stottlemyre | Bob Tewksbury | Mike Trombley | Xavier Hernandez | Rick Aguilera | 819 | 782 | 37 |
| 1998-09-06 | vs MIN | 142 | L 5-6 | 75-67 | 2 | 35,328 | Esteban Loaiza | Eric Milton | Hector Carrasco | Xavier Hernandez | Rick Aguilera | 824 | 788 | 36 |
| 1998-09-07 | vs MIN | 143 | W 6-0 | 76-67 | 2 | 24,519 | Rick Helling | LaTroy Hawkins | Rick Helling | LaTroy Hawkins | | 830 | 788 | 42 |
| 1998-09-08 | vs KCA | 144 | W 7-6 | 77-67 | 2 | 22,336 | John Burkett | Jose Rosado | Danny Patterson | Jeff Montgomery | | 837 | 794 | 43 |
| 1998-09-09 | vs KCA | 145 | W 8-0 | 78-67 | 2 | 28,441 | Aaron Sele | Pat Rapp | Aaron Sele | Pat Rapp | | 845 | 794 | 51 |
| 1998-09-11 | @ TBA | 146 | L 2-3 | 78-68 | 2 | 28,522 | Todd Stottlemyre | Tony Saunders | Tony Saunders | Todd Stottlemyre | Roberto Hernandez | 847 | 797 | 50 |
| 1998-09-12 | @ TBA | 147 | W 8-2 | 79-68 | 2 | 31,278 | Rick Helling | Julio Santana | Rick Helling | Julio Santana | | 855 | 799 | 56 |
| 1998-09-13 | @ TBA | 148 | L 5-10 | 79-69 | 2 | 34,007 | Esteban Loaiza | Bryan Rekar | Rick White | Esteban Loaiza | | 860 | 809 | 51 |
| 1998-09-14 | @ BAL | 149 | L 0-1 | 79-70 | 2 | 41,032 | Aaron Sele | Juan Guzman | Alan Mills | Xavier Hernandez | Armando Benitez | 860 | 810 | 50 |
| 1998-09-15 | @ BAL | 150 | W 6-5 | 80-70 | 2 | 41,363 | Esteban Loaiza | Chris Fussell | Tim Crabtree | Armando Benitez | John Wetteland | 866 | 815 | 51 |
| 1998-09-16 | vs ANA | 151 | W 5-3 | 81-70 | 2 | 37,481 | Todd Stottlemyre | Chuck Finley | Todd Stottlemyre | Chuck Finley | | 871 | 818 | 53 |
| 1998-09-17 | vs ANA | 152 | W 7-6 | 82-70 | 1 | 45,928 | Rick Helling | Steve Sparks | Tim Crabtree | Pep Harris | John Wetteland | 878 | 824 | 54 |
| 1998-09-18 | vs OAK | 153 | W 3-1 | 83-70 | 1 | 40,874 | John Burkett | Mike Oquist | John Burkett | Mike Oquist | John Wetteland | 881 | 825 | 56 |
| 1998-09-19 | vs OAK | 154 | L 4-8 | 83-71 | 1 | 46,036 | Aaron Sele | Jimmy Haynes | Jimmy Haynes | Aaron Sele | | 885 | 833 | 52 |
| 1998-09-20 | vs OAK | 155 | L 3-6 | 83-72 | 2 | 37,606 | Esteban Loaiza | Kenny Rogers | Kenny Rogers | Esteban Loaiza | Billy Taylor | 888 | 839 | 49 |
| 1998-09-21 | @ ANA | 156 | W 9-1 | 84-72 | 1 | 33,487 | Todd Stottlemyre | Steve Sparks | Todd Stottlemyre | Steve Sparks | | 897 | 840 | 57 |
| 1998-09-22 | @ ANA | 157 | W 9-1 | 85-72 | 1 | 38,987 | Rick Helling | Chuck Finley | Rick Helling | Chuck Finley | | 906 | 841 | 65 |
| 1998-09-23 | @ ANA | 158 | W 7-1 | 86-72 | 1 | 42,776 | John Burkett | Ken Hill | John Burkett | Ken Hill | | 913 | 842 | 71 |
| 1998-09-24 | @ SEA | 159 | W 9-3 | 87-72 | 1 | 22,891 | Aaron Sele | Mac Suzuki | Aaron Sele | Mac Suzuki | | 922 | 845 | 77 |
| 1998-09-25 | @ SEA | 160 | L 4-15 | 87-73 | 1 | 39,325 | Esteban Loaiza | Paul Abbott | Paul Abbott | Esteban Loaiza | | 926 | 860 | 66 |
| 1998-09-26 | @ SEA | 161 | L 2-5 | 87-74 | 1 | 33,147 | Eric Gunderson | Jeff Fassero | Jeff Fassero | Eric Gunderson | Mike Timlin | 928 | 865 | 63 |
| 1998-09-27 | @ SEA | 162 | W 12-6 | 88-74 | 1 | 37,986 | Jonathan Johnson | Paul Spoljaric | Tony Fossas | Paul Spoljaric | | 940 | 871 | 69 |