| 1991-04-09 | vs CAL | 1 | L 2-3 | 0-1 | 6 | 53,671 | Erik Hanson | Chuck Finley | Chuck Finley | Erik Hanson | Bryan Harvey | 2 | 3 | -1 |
| 1991-04-10 | vs CAL | 2 | L 3-5 | 0-2 | 6 | 16,977 | Randy Johnson | Kirk McCaskill | Kirk McCaskill | Randy Johnson | Bryan Harvey | 5 | 8 | -3 |
| 1991-04-11 | vs CAL | 3 | L 0-5 | 0-3 | 6 | 11,373 | Brian Holman | Mark Langston | Mark Langston | Brian Holman | Jeff Robinson | 5 | 13 | -8 |
| 1991-04-12 | @ OAK | 4 | L 1-6 | 0-4 | 6 | 36,112 | Scott Bankhead | Mike Moore | Mike Moore | Scott Bankhead | | 6 | 19 | -13 |
| 1991-04-13 | @ OAK | 5 | L 2-4 | 0-5 | 6 | 38,126 | Rich DeLucia | Kirk Dressendorfer | Kirk Dressendorfer | Rich DeLucia | Dennis Eckersley | 8 | 23 | -15 |
| 1991-04-14 | @ OAK | 6 | L 6-7 | 0-6 | 7 | 28,949 | Erik Hanson | Dave Stewart | Dana Allison | Michael Jackson | | 14 | 30 | -16 |
| 1991-04-15 | vs MIN | 7 | W 8-4 | 1-6 | 7 | 15,120 | Randy Johnson | Allan Anderson | Randy Johnson | Allan Anderson | | 22 | 34 | -12 |
| 1991-04-16 | vs MIN | 8 | W 3-0 | 2-6 | 7 | 8,837 | Brian Holman | Scott Erickson | Brian Holman | Scott Erickson | | 25 | 34 | -9 |
| 1991-04-17 | vs MIN | 9 | W 4-3 | 3-6 | 5 | 9,628 | Scott Bankhead | Kevin Tapani | Michael Jackson | Rick Aguilera | | 29 | 37 | -8 |
| 1991-04-19 | vs OAK | 10 | W 11-7 | 4-6 | 5 | 24,009 | Rich DeLucia | Dave Stewart | Rich DeLucia | Dave Stewart | Rob Murphy | 40 | 44 | -4 |
| 1991-04-20 | vs OAK | 11 | W 3-2 | 5-6 | 5 | 51,412 | Erik Hanson | Bob Welch | Erik Hanson | Dennis Eckersley | | 43 | 46 | -3 |
| 1991-04-21 | vs OAK | 12 | W 7-2 | 6-6 | 4 | 30,191 | Randy Johnson | Joe Slusarski | Randy Johnson | Dana Allison | | 50 | 48 | 2 |
| 1991-04-22 | @ CAL | 13 | W 4-3 | 7-6 | 4 | 19,857 | Brian Holman | Jim Abbott | Brian Holman | Jim Abbott | Michael Jackson | 54 | 51 | 3 |
| 1991-04-23 | @ CAL | 14 | W 2-0 | 8-6 | 3 | 20,446 | Scott Bankhead | Scott Lewis | Scott Bankhead | Scott Lewis | Russ Swan | 56 | 51 | 5 |
| 1991-04-24 | @ CAL | 15 | L 5-9 | 8-7 | 5 | 24,638 | Rich DeLucia | Chuck Finley | Chuck Finley | Rich DeLucia | Bryan Harvey | 61 | 60 | 1 |
| 1991-04-25 | @ MIN | 16 | L 3-4 | 8-8 | 5 | 10,230 | Erik Hanson | Allan Anderson | Steve Bedrosian | Michael Jackson | | 64 | 64 | 0 |
| 1991-04-26 | @ MIN | 17 | L 0-6 | 8-9 | 5 | 15,965 | Randy Johnson | Scott Erickson | Scott Erickson | Randy Johnson | | 64 | 70 | -6 |
| 1991-04-27 | @ MIN | 18 | L 2-7 | 8-10 | 7 | 16,247 | Brian Holman | Kevin Tapani | Kevin Tapani | Brian Holman | | 66 | 77 | -11 |
| 1991-04-28 | @ MIN | 19 | L 2-8 | 8-11 | 7 | 18,039 | Scott Bankhead | Jack Morris | Jack Morris | Scott Bankhead | | 68 | 85 | -17 |
| 1991-04-29 | @ BAL | 20 | W 10-1 | 9-11 | 6 | 18,892 | Rich DeLucia | Dave Johnson | Rich DeLucia | Dave Johnson | | 78 | 86 | -8 |
| 1991-04-30 | @ BAL | 21 | W 6-3 | 10-11 | 5 | 18,743 | Erik Hanson | Jeff Ballard | Erik Hanson | Jeff Ballard | Russ Swan | 84 | 89 | -5 |
| 1991-05-01 | @ BAL | 22 | L 1-2 | 10-12 | 6 | 19,918 | Randy Johnson | Jose Mesa | Jose Mesa | Randy Johnson | Gregg Olson | 85 | 91 | -6 |
| 1991-05-03 | vs NYA | 23 | L 0-5 | 10-13 | 6 | 22,884 | Brian Holman | Scott Sanderson | Scott Sanderson | Brian Holman | | 85 | 96 | -11 |
| 1991-05-04 | vs NYA | 24 | W 3-2 | 11-13 | 6 | 53,755 | Scott Bankhead | Chuck Cary | Scott Bankhead | Chuck Cary | Michael Jackson | 88 | 98 | -10 |
| 1991-05-05 | vs NYA | 25 | W 5-4 | 12-13 | 6 | 24,391 | Rich DeLucia | Dave Eiland | Bill Krueger | Rich Monteleone | | 93 | 102 | -9 |
| 1991-05-06 | vs NYA | 26 | W 4-2 | 13-13 | 3 | 24,210 | Erik Hanson | Tim Leary | Erik Hanson | Tim Leary | Bill Swift | 97 | 104 | -7 |
| 1991-05-07 | vs CLE | 27 | W 7-6 | 14-13 | 4 | 9,511 | Randy Johnson | Tom Candiotti | Michael Jackson | Doug Jones | | 104 | 110 | -6 |
| 1991-05-08 | vs CLE | 28 | W 6-2 | 15-13 | 3 | 10,930 | Brian Holman | Charles Nagy | Brian Holman | Charles Nagy | Bill Swift | 110 | 112 | -2 |
| 1991-05-10 | vs BAL | 29 | W 3-1 | 16-13 | 3 | 24,553 | Scott Bankhead | Jeff Ballard | Rich DeLucia | Jeff Ballard | Michael Jackson | 113 | 113 | 0 |
| 1991-05-11 | vs BAL | 30 | L 5-11 | 16-14 | 3 | 26,338 | Erik Hanson | Jose Mesa | Jose Mesa | Bill Krueger | | 118 | 124 | -6 |
| 1991-05-12 | vs BAL | 31 | W 5-4 | 17-14 | 2 | 16,484 | Randy Johnson | Ben McDonald | Michael Jackson | Gregg Olson | | 123 | 128 | -5 |
| 1991-05-14 | @ CLE | 32 | W 2-1 | 18-14 | 2 | 5,962 | Brian Holman | Rod Nichols | Brian Holman | Rod Nichols | Bill Swift | 125 | 129 | -4 |
| 1991-05-15 | @ CLE | 33 | W 6-4 | 19-14 | 2 | 6,327 | Rich DeLucia | Eric King | Rich DeLucia | Eric King | Bill Swift | 131 | 133 | -2 |
| 1991-05-16 | @ CLE | 34 | W 3-1 | 20-14 | 2 | 5,665 | Bill Krueger | Greg Swindell | Michael Jackson | Greg Swindell | | 134 | 134 | 0 |
| 1991-05-17 | @ NYA | 35 | W 1-0 | 21-14 | 1 | 16,810 | Randy Johnson | Tim Leary | Randy Johnson | Tim Leary | Bill Swift | 135 | 134 | 1 |
| 1991-05-18 | @ NYA | 36 | W 4-1 | 22-14 | 1 | 23,017 | Pat Rice | Scott Sanderson | Pat Rice | Scott Sanderson | | 139 | 135 | 4 |
| 1991-05-19 | @ NYA | 37 | L 2-3 | 22-15 | 2 | 29,581 | Brian Holman | Pascual Perez | Steve Howe | Brian Holman | Lee Guetterman | 141 | 138 | 3 |
| 1991-05-20 | @ KCA | 38 | W 8-6 | 23-15 | 1 | 27,088 | Rich DeLucia | Bret Saberhagen | Russ Swan | Jeff Montgomery | Michael Jackson | 149 | 144 | 5 |
| 1991-05-21 | @ KCA | 39 | L 3-4 | 23-16 | 1 | 19,954 | Bill Krueger | Kevin Appier | Kevin Appier | Bill Krueger | | 152 | 148 | 4 |
| 1991-05-22 | @ KCA | 40 | L 1-3 | 23-17 | 3 | 23,618 | Randy Johnson | Tom Gordon | Tom Gordon | Randy Johnson | | 153 | 151 | 2 |
| 1991-05-24 | vs TEX | 41 | L 3-7 | 23-18 | 3 | 30,222 | Brian Holman | Kenny Rogers | Kenny Rogers | Brian Holman | John Barfield | 156 | 158 | -2 |
| 1991-05-25 | vs TEX | 42 | L 6-8 | 23-19 | 3 | 30,242 | Rich DeLucia | Scott Chiamparino | John Barfield | Russ Swan | | 162 | 166 | -4 |
| 1991-05-26 | vs TEX | 43 | L 4-6 | 23-20 | 4 | 30,347 | Bill Krueger | Bobby Witt | Bobby Witt | Bill Swift | Jeff Russell | 166 | 172 | -6 |
| 1991-05-27 | vs KCA | 44 | L 3-6 | 23-21 | 4 | 34,240 | Randy Johnson | Kevin Appier | Kevin Appier | Randy Johnson | | 169 | 178 | -9 |
| 1991-05-28 | vs KCA | 45 | L 5-6 | 23-22 | 4 | 12,110 | Erik Hanson | Tom Gordon | Tom Gordon | Erik Hanson | Mark Davis | 174 | 184 | -10 |
| 1991-05-29 | vs KCA | 46 | W 8-0 | 24-22 | 4 | 15,722 | Brian Holman | Mike Boddicker | Brian Holman | Mike Boddicker | | 182 | 184 | -2 |
| 1991-05-30 | @ TEX | 47 | W 11-4 | 25-22 | 4 | 29,819 | Rich DeLucia | Kenny Rogers | Rich DeLucia | Kenny Rogers | | 193 | 188 | 5 |
| 1991-05-31 | @ TEX | 48 | L 6-7 | 25-23 | 4 | 36,386 | Scott Bankhead | Gerald Alexander | Gerald Alexander | Scott Bankhead | Jeff Russell | 199 | 195 | 4 |
| 1991-06-01 | @ TEX | 49 | W 12-8 | 26-23 | 4 | 36,278 | Randy Johnson | Kevin Brown | Russ Swan | Kevin Brown | Michael Jackson | 211 | 203 | 8 |
| 1991-06-04 | @ DET | 50 | W 8-6 | 27-23 | 4 | 11,993 | Brian Holman | John Cerutti | Brian Holman | John Cerutti | Michael Jackson | 219 | 209 | 10 |
| 1991-06-05 | @ DET | 51 | L 1-7 | 27-24 | 4 | 12,609 | Rich DeLucia | Kevin Ritz | Jerry Gleaton | Rich DeLucia | Paul Gibson | 220 | 216 | 4 |
| 1991-06-06 | @ DET | 52 | L 4-5 | 27-25 | 5 | 15,600 | Scott Bankhead | Bill Gullickson | Bill Gullickson | Scott Bankhead | Mike Henneman | 224 | 221 | 3 |
| 1991-06-07 | vs MIL | 53 | W 2-1 | 28-25 | 5 | 16,968 | Bill Krueger | Teddy Higuera | Bill Krueger | Teddy Higuera | Michael Jackson | 226 | 222 | 4 |
| 1991-06-08 | vs MIL | 54 | W 6-2 | 29-25 | 4 | 25,835 | Rich DeLucia | Bill Wegman | Rich DeLucia | Bill Wegman | Dave Burba | 232 | 224 | 8 |
| 1991-06-09 | vs MIL | 55 | W 6-1 | 30-25 | 4 | 41,397 | Brian Holman | Jaime Navarro | Brian Holman | Jaime Navarro | | 238 | 225 | 13 |
| 1991-06-10 | vs BOS | 56 | L 2-6 | 30-26 | 4 | 32,082 | Randy Johnson | Mike Gardiner | Mike Gardiner | Randy Johnson | | 240 | 231 | 9 |
| 1991-06-11 | vs BOS | 57 | L 5-8 | 30-27 | 4 | 20,833 | Scott Bankhead | Danny Darwin | Danny Darwin | Scott Bankhead | Jeff Reardon | 245 | 239 | 6 |
| 1991-06-12 | vs BOS | 58 | W 5-3 | 31-27 | 4 | 19,641 | Bill Krueger | Greg Harris | Bill Krueger | Greg Harris | Michael Jackson | 250 | 242 | 8 |
| 1991-06-13 | vs DET | 59 | W 6-5 | 32-27 | 4 | 15,557 | Rich DeLucia | Walt Terrell | Bill Swift | Paul Gibson | Michael Jackson | 256 | 247 | 9 |
| 1991-06-14 | vs DET | 60 | L 1-5 | 32-28 | 5 | 20,616 | Brian Holman | Dan Gakeler | Dan Gakeler | Brian Holman | | 257 | 252 | 5 |
| 1991-06-15 | vs DET | 61 | W 15-2 | 33-28 | 5 | 27,417 | Randy Johnson | Kevin Ritz | Randy Johnson | Kevin Ritz | Bill Swift | 272 | 254 | 18 |
| 1991-06-16 | vs DET | 62 | L 3-7 | 33-29 | 5 | 53,287 | Pat Rice | Bill Gullickson | Bill Gullickson | Pat Rice | | 275 | 261 | 14 |
| 1991-06-18 | @ BOS | 63 | W 2-1 | 34-29 | 4 | 33,948 | Bill Krueger | Danny Darwin | Bill Krueger | Jeff Reardon | Michael Jackson | 277 | 262 | 15 |
| 1991-06-19 | @ BOS | 64 | W 4-3 | 35-29 | 4 | 33,251 | Rich DeLucia | Roger Clemens | Russ Swan | Roger Clemens | Michael Jackson | 281 | 265 | 16 |
| 1991-06-20 | @ MIL | 65 | L 0-4 | 35-30 | 5 | 19,174 | Brian Holman | Jaime Navarro | Jaime Navarro | Brian Holman | | 281 | 269 | 12 |
| 1991-06-21 | @ MIL | 66 | W 5-1 | 36-30 | 4 | 18,409 | Randy Johnson | Chris Bosio | Randy Johnson | Chris Bosio | | 286 | 270 | 16 |
| 1991-06-22 | @ MIL | 67 | W 5-0 | 37-30 | 3 | 25,260 | Erik Hanson | Don August | Erik Hanson | Don August | | 291 | 270 | 21 |
| 1991-06-23 | @ MIL | 68 | L 2-5 | 37-31 | 3 | 25,159 | Bill Krueger | Teddy Higuera | Teddy Higuera | Bill Krueger | Dan Plesac | 293 | 275 | 18 |
| 1991-06-24 | @ CHA | 69 | L 2-6 | 37-32 | 4 | 42,552 | Rich DeLucia | Greg Hibbard | Greg Hibbard | Rich DeLucia | Scott Radinsky | 295 | 281 | 14 |
| 1991-06-25 | @ CHA | 70 | L 0-4 | 37-33 | 5 | 36,971 | Dave Burba | Jack McDowell | Jack McDowell | Dave Burba | | 295 | 285 | 10 |
| 1991-06-26 | @ CHA | 71 | W 5-4 | 38-33 | 5 | 35,103 | Randy Johnson | Ramon Garcia | Randy Johnson | Ramon Garcia | Michael Jackson | 300 | 289 | 11 |
| 1991-06-27 | @ CHA | 72 | L 2-5 | 38-34 | 5 | 37,065 | Erik Hanson | Alex Fernandez | Alex Fernandez | Erik Hanson | Bobby Thigpen | 302 | 294 | 8 |
| 1991-06-28 | @ TOR | 73 | W 3-1 | 39-34 | 5 | 50,297 | Bill Krueger | Tom Candiotti | Bill Krueger | Tom Candiotti | Michael Jackson | 305 | 295 | 10 |
| 1991-06-29 | @ TOR | 74 | L 0-4 | 39-35 | 6 | 50,268 | Rich DeLucia | Jimmy Key | Mike Timlin | Rich DeLucia | Duane Ward | 305 | 299 | 6 |
| 1991-06-30 | @ TOR | 75 | L 1-6 | 39-36 | 6 | 50,298 | Brian Holman | Todd Stottlemyre | Todd Stottlemyre | Brian Holman | | 306 | 305 | 1 |
| 1991-07-01 | @ TOR | 76 | L 3-4 | 39-37 | 6 | 50,270 | Randy Johnson | David Wells | Jim Acker | Michael Jackson | | 309 | 309 | 0 |
| 1991-07-02 | vs CHA | 77 | L 4-5 | 39-38 | 6 | 16,444 | Erik Hanson | Alex Fernandez | Melido Perez | Dave Burba | | 313 | 314 | -1 |
| 1991-07-03 | vs CHA | 78 | L 2-3 | 39-39 | 6 | 13,856 | Bill Krueger | Charlie Hough | Donn Pall | Calvin Jones | Bobby Thigpen | 315 | 317 | -2 |
| 1991-07-04 | vs CHA | 79 | W 3-2 | 40-39 | 6 | 15,104 | Rich DeLucia | Greg Hibbard | Rich DeLucia | Greg Hibbard | Rob Murphy | 318 | 319 | -1 |
| 1991-07-05 | vs TOR | 80 | L 1-2 | 40-40 | 6 | 21,647 | Brian Holman | Todd Stottlemyre | Bob Macdonald | Brian Holman | Tom Henke | 319 | 321 | -2 |
| 1991-07-06 | vs TOR | 81 | L 3-4 | 40-41 | 6 | 48,570 | Randy Johnson | David Wells | Mike Timlin | Russ Swan | Tom Henke | 322 | 325 | -3 |
| 1991-07-07 | vs TOR | 82 | L 2-5 | 40-42 | 6 | 27,812 | Erik Hanson | Juan Guzman | Juan Guzman | Erik Hanson | | 324 | 330 | -6 |
| 1991-07-11 | vs CLE | 83 | W 6-0 | 41-42 | 6 | 12,342 | Brian Holman | Charles Nagy | Brian Holman | Charles Nagy | Bill Swift | 330 | 330 | 0 |
| 1991-07-12 | vs CLE | 84 | W 7-0 | 42-42 | 6 | 15,211 | Randy Johnson | Rod Nichols | Randy Johnson | Rod Nichols | | 337 | 330 | 7 |
| 1991-07-13 | vs CLE | 85 | L 3-6 | 42-43 | 6 | 20,726 | Erik Hanson | Greg Swindell | Greg Swindell | Michael Jackson | | 340 | 336 | 4 |
| 1991-07-14 | vs CLE | 86 | W 14-3 | 43-43 | 6 | 15,441 | Rich DeLucia | Mike York | Rich DeLucia | Mike York | | 354 | 339 | 15 |
| 1991-07-15 | vs NYA | 87 | W 5-1 | 44-43 | 6 | 36,027 | Bill Krueger | Greg Cadaret | Bill Krueger | Greg Cadaret | | 359 | 340 | 19 |
| 1991-07-16 | vs NYA | 88 | W 5-0 | 45-43 | 6 | 25,641 | Brian Holman | Scott Sanderson | Brian Holman | Scott Sanderson | | 364 | 340 | 24 |
| 1991-07-17 | @ MIL | 89 | L 1-6 | 45-44 | 6 | 16,059 | Randy Johnson | Bill Wegman | Bill Wegman | Randy Johnson | | 365 | 346 | 19 |
| 1991-07-18 | @ MIL | 90 | W 12-0 | 46-44 | 6 | 26,621 | Erik Hanson | Jaime Navarro | Erik Hanson | Jaime Navarro | | 377 | 346 | 31 |
| 1991-07-19 | @ BAL | 91 | L 1-4 | 46-45 | 6 | 39,384 | Rich DeLucia | Roy Smith | Roy Smith | Rich DeLucia | Gregg Olson | 378 | 350 | 28 |
| 1991-07-20 | @ BAL | 92 | W 5-1 | 47-45 | 6 | 35,535 | Bill Krueger | Jeff Ballard | Bill Krueger | Jeff Ballard | | 383 | 351 | 32 |
| 1991-07-21 | @ BAL | 93 | W 6-4 | 48-45 | 6 | 32,901 | Brian Holman | Jeff Robinson | Russ Swan | Jeff Robinson | Bill Swift | 389 | 355 | 34 |
| 1991-07-23 | @ NYA | 94 | W 6-1 | 49-45 | 6 | 17,293 | Randy Johnson | Scott Kamieniecki | Randy Johnson | Scott Kamieniecki | | 395 | 356 | 39 |
| 1991-07-24 | @ NYA | 95 | L 2-10 | 49-46 | 6 | 21,585 | Erik Hanson | Jeff Johnson | Jeff Johnson | Erik Hanson | | 397 | 366 | 31 |
| 1991-07-25 | @ NYA | 96 | W 6-3 | 50-46 | 5 | 24,559 | Bill Krueger | Wade Taylor | Bill Krueger | Wade Taylor | Rob Murphy | 403 | 369 | 34 |
| 1991-07-26 | @ CLE | 97 | W 7-4 | 51-46 | 5 | 12,839 | Rich DeLucia | Denis Boucher | Rich DeLucia | Denis Boucher | Mike Schooler | 410 | 373 | 37 |
| 1991-07-27 | @ CLE | 98 | L 1-6 | 51-47 | 5 | 32,979 | Brian Holman | Charles Nagy | Charles Nagy | Brian Holman | | 411 | 379 | 32 |
| 1991-07-28 | @ CLE | 99 | W 6-5 | 52-47 | 5 | 17,484 | Randy Johnson | Rod Nichols | Randy Johnson | Mike York | Bill Swift | 417 | 384 | 33 |
| 1991-07-29 | vs BAL | 100 | W 11-4 | 53-47 | 5 | 31,910 | Erik Hanson | Bob Milacki | Erik Hanson | Bob Milacki | | 428 | 388 | 40 |
| 1991-07-30 | vs BAL | 101 | W 8-2 | 54-47 | 5 | 18,725 | Bill Krueger | Roy Smith | Bill Krueger | Roy Smith | | 436 | 390 | 46 |
| 1991-07-31 | vs BAL | 102 | L 2-4 | 54-48 | 5 | 22,503 | Rich DeLucia | Dave Johnson | Mike Flanagan | Bill Swift | Gregg Olson | 438 | 394 | 44 |
| 1991-08-02 | @ CAL | 103 | W 4-3 | 55-48 | 5 | 27,434 | Brian Holman | Jim Abbott | Michael Jackson | Jim Abbott | Mike Schooler | 442 | 397 | 45 |
| 1991-08-03 | @ CAL | 104 | W 9-3 | 56-48 | 5 | 28,942 | Randy Johnson | Kirk McCaskill | Randy Johnson | Kirk McCaskill | Bill Swift | 451 | 400 | 51 |
| 1991-08-04 | @ CAL | 105 | W 5-2 | 57-48 | 4 | 27,393 | Erik Hanson | Mark Langston | Michael Jackson | Mike Fetters | Mike Schooler | 456 | 402 | 54 |
| 1991-08-05 | @ OAK | 106 | L 0-3 | 57-49 | 4 | 27,561 | Bill Krueger | Ron Darling | Ron Darling | Bill Krueger | Dennis Eckersley | 456 | 405 | 51 |
| 1991-08-06 | @ OAK | 107 | L 0-3 | 57-50 | 5 | 32,235 | Rich DeLucia | Mike Moore | Mike Moore | Rich DeLucia | Dennis Eckersley | 456 | 408 | 48 |
| 1991-08-07 | @ OAK | 108 | L 1-6 | 57-51 | 5 | 40,251 | Brian Holman | Bob Welch | Bob Welch | Brian Holman | | 457 | 414 | 43 |
| 1991-08-09 | vs MIN | 109 | L 2-5 | 57-52 | 6 | 31,112 | Randy Johnson | David West | David West | Randy Johnson | Rick Aguilera | 459 | 419 | 40 |
| 1991-08-10 | vs MIN | 110 | W 8-0 | 58-52 | 5 | 29,548 | Erik Hanson | Scott Erickson | Erik Hanson | Scott Erickson | | 467 | 419 | 48 |
| 1991-08-11 | vs MIN | 111 | L 2-5 | 58-53 | 6 | 31,007 | Bill Krueger | Kevin Tapani | Kevin Tapani | Bill Krueger | | 469 | 424 | 45 |
| 1991-08-12 | vs OAK | 112 | W 6-3 | 59-53 | 5 | 41,967 | Rich DeLucia | Bob Welch | Rich DeLucia | Bob Welch | | 475 | 427 | 48 |
| 1991-08-13 | vs OAK | 113 | W 5-2 | 60-53 | 5 | 22,976 | Brian Holman | Dave Stewart | Brian Holman | Dave Stewart | Mike Schooler | 480 | 429 | 51 |
| 1991-08-14 | vs OAK | 114 | W 4-0 | 61-53 | 5 | 25,419 | Randy Johnson | Joe Slusarski | Randy Johnson | Joe Slusarski | | 484 | 429 | 55 |
| 1991-08-15 | vs OAK | 115 | W 8-6 | 62-53 | 4 | 32,006 | Erik Hanson | Ron Darling | Calvin Jones | Steve Chitren | Mike Schooler | 492 | 435 | 57 |
| 1991-08-16 | vs CAL | 116 | W 5-3 | 63-53 | 4 | 27,461 | Bill Krueger | Joe Grahe | Bill Krueger | Joe Grahe | Rob Murphy | 497 | 438 | 59 |
| 1991-08-17 | vs CAL | 117 | L 1-4 | 63-54 | 4 | 33,107 | Rich DeLucia | Chuck Finley | Chuck Finley | Rich DeLucia | Bryan Harvey | 498 | 442 | 56 |
| 1991-08-18 | vs CAL | 118 | L 3-4 | 63-55 | 4 | 22,474 | Brian Holman | Jim Abbott | Jim Abbott | Brian Holman | Bryan Harvey | 501 | 446 | 55 |
| 1991-08-19 | vs CAL | 119 | W 7-1 | 64-55 | 4 | 33,471 | Randy Johnson | Kirk McCaskill | Randy Johnson | Kirk McCaskill | | 508 | 447 | 61 |
| 1991-08-20 | @ MIN | 120 | L 5-10 | 64-56 | 4 | 32,090 | Erik Hanson | Scott Erickson | Scott Erickson | Erik Hanson | Mark Guthrie | 513 | 457 | 56 |
| 1991-08-21 | @ MIN | 121 | L 1-9 | 64-57 | 4 | 30,631 | Bill Krueger | Kevin Tapani | Kevin Tapani | Bill Krueger | | 514 | 466 | 48 |
| 1991-08-22 | @ MIN | 122 | L 4-5 | 64-58 | 4 | 35,874 | Rich DeLucia | Jack Morris | Rick Aguilera | Mike Schooler | | 518 | 471 | 47 |
| 1991-08-23 | @ DET | 123 | L 6-8 | 64-59 | 5 | 30,214 | Brian Holman | Bill Gullickson | Bill Gullickson | Brian Holman | Jeff Kaiser | 524 | 479 | 45 |
| 1991-08-24 | @ DET | 124 | L 2-7 | 64-60 | 6 | 42,135 | Randy Johnson | Frank Tanana | Frank Tanana | Randy Johnson | | 526 | 486 | 40 |
| 1991-08-25 | @ DET | 125 | L 3-4 | 64-61 | 6 | 29,480 | Erik Hanson | Walt Terrell | Walt Terrell | Mike Schooler | | 529 | 490 | 39 |
| 1991-08-26 | vs MIL | 126 | W 5-4 | 65-61 | 6 | 22,079 | Bill Krueger | Mike Ignasiak | Mike Schooler | Doug Henry | | 534 | 494 | 40 |
| 1991-08-27 | vs MIL | 127 | W 6-4 | 66-61 | 6 | 12,067 | Rich DeLucia | Don August | Rich DeLucia | Don August | Michael Jackson | 540 | 498 | 42 |
| 1991-08-28 | vs MIL | 128 | W 7-6 | 67-61 | 6 | 11,470 | Brian Holman | Jaime Navarro | Brian Holman | Jaime Navarro | Bill Swift | 547 | 504 | 43 |
| 1991-08-30 | vs BOS | 129 | L 2-3 | 67-62 | 6 | 29,889 | Erik Hanson | Joe Hesketh | Joe Hesketh | Erik Hanson | Jeff Reardon | 549 | 507 | 42 |
| 1991-08-31 | vs BOS | 130 | L 1-4 | 67-63 | 6 | 32,840 | Bill Krueger | Roger Clemens | Roger Clemens | Bill Krueger | | 550 | 511 | 39 |
| 1991-09-01 | vs BOS | 131 | L 2-13 | 67-64 | 6 | 19,141 | Randy Johnson | Kevin Morton | Kevin Morton | Randy Johnson | | 552 | 524 | 28 |
| 1991-09-02 | vs DET | 132 | L 5-12 | 67-65 | 6 | 20,208 | Rich DeLucia | Bill Gullickson | Bill Gullickson | Rich DeLucia | Paul Gibson | 557 | 536 | 21 |
| 1991-09-03 | vs DET | 133 | W 1-0 | 68-65 | 6 | 11,441 | Brian Holman | Scott Aldred | Brian Holman | Scott Aldred | Bill Swift | 558 | 536 | 22 |
| 1991-09-05 | @ BOS | 134 | L 3-4 | 68-66 | 6 | 30,200 | Erik Hanson | Roger Clemens | Jeff Reardon | Rob Murphy | | 561 | 540 | 21 |
| 1991-09-06 | @ BOS | 135 | L 5-6 | 68-67 | 6 | 33,002 | Bill Krueger | Matt Young | Dennis Lamp | Michael Jackson | Jeff Reardon | 566 | 546 | 20 |
| 1991-09-07 | @ BOS | 136 | L 10-11 | 68-68 | 6 | 33,119 | Randy Johnson | Kevin Morton | Tom Bolton | Calvin Jones | Jeff Reardon | 576 | 557 | 19 |
| 1991-09-08 | @ BOS | 137 | L 6-17 | 68-69 | 7 | 32,979 | Rich DeLucia | Mike Gardiner | Mike Gardiner | Rich DeLucia | | 582 | 574 | 8 |
| 1991-09-10 | @ TOR | 138 | W 5-4 | 69-69 | 6 | 50,196 | Brian Holman | Todd Stottlemyre | Brian Holman | Todd Stottlemyre | Calvin Jones | 587 | 578 | 9 |
| 1991-09-11 | @ TOR | 139 | W 7-3 | 70-69 | 6 | 50,321 | Erik Hanson | Jimmy Key | Erik Hanson | Jimmy Key | | 594 | 581 | 13 |
| 1991-09-13 | @ KCA | 140 | L 2-3 | 70-70 | 6 | 20,519 | Randy Johnson | Luis Aquino | Jeff Montgomery | Michael Jackson | | 596 | 584 | 12 |
| 1991-09-14 | @ KCA | 141 | W 4-3 | 71-70 | 6 | 27,582 | Bill Krueger | Kevin Appier | Michael Jackson | Steve Crawford | Bill Swift | 600 | 587 | 13 |
| 1991-09-15 | @ KCA | 142 | W 14-7 | 72-70 | 6 | 20,019 | Rich DeLucia | Mike Boddicker | Rich DeLucia | Mike Boddicker | | 614 | 594 | 20 |
| 1991-09-16 | vs TOR | 143 | W 6-5 | 73-70 | 5 | 55,612 | Brian Holman | Jimmy Key | Russ Swan | Bob Macdonald | | 620 | 599 | 21 |
| 1991-09-17 | vs TOR | 144 | W 5-4 | 74-70 | 5 | 29,115 | Erik Hanson | Juan Guzman | Mike Schooler | Jim Acker | | 625 | 603 | 22 |
| 1991-09-18 | vs TOR | 145 | L 3-5 | 74-71 | 6 | 30,200 | Randy Johnson | Tom Candiotti | Duane Ward | Scott Bankhead | Jim Acker | 628 | 608 | 20 |
| 1991-09-19 | vs KCA | 146 | W 10-5 | 75-71 | 5 | 26,265 | Bill Krueger | Kevin Appier | Dave Burba | Tom Gordon | Bill Swift | 638 | 613 | 25 |
| 1991-09-20 | vs KCA | 147 | L 0-3 | 75-72 | 6 | 14,141 | Rich DeLucia | Mike Boddicker | Mike Boddicker | Rich DeLucia | Jeff Montgomery | 638 | 616 | 22 |
| 1991-09-21 | vs KCA | 148 | W 4-1 | 76-72 | 5 | 14,393 | Dave Fleming | Mark Gubicza | Dave Fleming | Mark Gubicza | Mike Schooler | 642 | 617 | 25 |
| 1991-09-22 | vs KCA | 149 | L 1-2 | 76-73 | 6 | 14,116 | Brian Holman | Bret Saberhagen | Bret Saberhagen | Brian Holman | | 643 | 619 | 24 |
| 1991-09-23 | vs TEX | 150 | L 4-11 | 76-74 | 6 | 49,486 | Randy Johnson | Brian Bohanon | Jeff Russell | Mike Schooler | | 647 | 630 | 17 |
| 1991-09-24 | vs TEX | 151 | L 7-8 | 76-75 | 6 | 21,862 | Bill Krueger | Kevin Brown | Jeff Russell | Michael Jackson | | 654 | 638 | 16 |
| 1991-09-25 | vs TEX | 152 | L 1-7 | 76-76 | 6 | 27,256 | Rich DeLucia | Nolan Ryan | Nolan Ryan | Rich DeLucia | | 655 | 645 | 10 |
| 1991-09-27 | @ CHA | 153 | W 10-8 | 77-76 | 6 | 33,023 | Dave Fleming | Jack McDowell | Russ Swan | Melido Perez | | 665 | 653 | 12 |
| 1991-09-28 | @ CHA | 154 | L 2-5 | 77-77 | 6 | 40,680 | Rich DeLucia | Greg Hibbard | Greg Hibbard | Rich DeLucia | Scott Radinsky | 667 | 658 | 9 |
| 1991-09-29 | @ CHA | 155 | W 2-1 | 78-77 | 6 | 33,096 | Randy Johnson | Charlie Hough | Randy Johnson | Charlie Hough | Bill Swift | 669 | 659 | 10 |
| 1991-09-30 | @ TEX | 156 | W 3-2 | 79-78 | 6 | 0 | Erik Hanson | Nolan Ryan | Mike Schooler | Wayne Rosenthal | Bill Swift | 672 | 661 | 11 |
| 1991-09-30 | @ TEX | 157 | L 0-2 | 79-78 | 6 | 19,651 | Bill Krueger | Brian Bohanon | Brian Bohanon | Bill Krueger | Jeff Russell | 672 | 663 | 9 |
| 1991-10-01 | @ TEX | 158 | W 8-1 | 80-78 | 6 | 12,808 | Dave Burba | Oil Can Boyd | Dave Burba | Oil Can Boyd | Calvin Jones | 680 | 664 | 16 |
| 1991-10-02 | @ TEX | 159 | W 4-3 | 81-78 | 6 | 12,273 | Dave Fleming | Jose Guzman | Scott Bankhead | Jose Guzman | Bill Swift | 684 | 667 | 17 |
| 1991-10-04 | vs CHA | 160 | W 6-4 | 82-78 | 6 | 55,300 | Randy Johnson | Charlie Hough | Calvin Jones | Charlie Hough | Mike Schooler | 690 | 671 | 19 |
| 1991-10-05 | vs CHA | 161 | W 10-0 | 83-78 | 5 | 32,923 | Bill Krueger | Ramon Garcia | Bill Krueger | Ramon Garcia | Gene Harris | 700 | 671 | 29 |
| 1991-10-06 | vs CHA | 162 | L 2-3 | 83-79 | 5 | 46,865 | Erik Hanson | Wilson Alvarez | Wilson Alvarez | Erik Hanson | Scott Radinsky | 702 | 674 | 28 |