The Men's 100m Breaststroke event at the 2003 Pan American Games took place on August 12, 2003 (Day 11 of the Games).
| 59.78 | 2003-07-21 |  Barcelona, Spain | |||
| 1:00.99 | 1999-08-02 |  Winnipeg, Canada |
| Place | Swimmer | Heats | Final | ||
|---|---|---|---|---|---|
| Time | Rank | Time | |||
| 1 | 1:02.04 | 1 | 1:00.95 | ||
| 2 | 1:02.15 | 2 | 1:01.71 | ||
| 3 | 1:02.77 | 3 | 1:01.88 SA | ||
| 4 | 1:03.03 | 5 | 1:02.13 | ||
| 5 | 1:02.98 | 4 | 1:02.81 | ||
| 6 | 1:03.92 | 7 | 1:03.44 | ||
| 7 | 1:03.83 | 6 | 1:03.55 | ||
| 8 | 1:03.96 | 8 | 1:03.65 | ||
| 9 | 1:45.27 | 20 | 1:03.82 | ||
| 10 | 1:05.38 | 10 | 1:04.01 | ||
| 11 | 1:05.69 | 12 | 1:05.43 | ||
| 12 | 1:05.12 | 9 | 1:05.47 | ||
| 13 | 1:06.54 | 13 | 1:05.63 | ||
| 14 | 1:05.39 | 11 | 1:05.65 | ||
| 15 | 1:07.02 | 14 | 1:06.66 | ||
| 16 | 1:07.44 | 15 | 1:07.34 | ||
| 17 | 1:07.64 | 16 | |||
| 18 | 1:09.28 | 17 | |||
| 19 | 1:10.29 | 18 | |||
| 20 | 1:10.78 | 19 | |||