| Event: | Men's 800 metres |
| Win Label: | Winning time |
The final of the Men's 800 metres event at the 2003 Pan American Games took place on Wednesday August 6, 2003, with the heats staged a day earlier. The Moroccan-born Canadian Achraf Tadili ran a very quick finish to win in a record time of 1:45.05, faster than the previous Pan Am Record (1:45.38) set by USA’s Johnny Gray four years earlier in Winnipeg. Brazil’s Osmar dos Santos (1:45.64) could not respond to his rival’s late surge and finished second, ahead of his compatriot Fabiano Peçanha (1:46.39).
| 1:41.11 | August 24, 1997 | ||||
| 1:45.38 | July 25, 1999 |  Winnipeg, Canada |
| Rank | Athlete | Heats | Final | |
|---|---|---|---|---|
| Time | Rank | Time | ||
| 1 | 1:49.70 | 6 | 1:45.05 | |
| 2 | 1:49.63 | 5 | 1:45.64 | |
| 3 | 1:49.34 | 3 | 1:46.39 | |
| 4 | 1:49.58 | 4 | 1:46.45 | |
| 5 | 1:49.78 | 7 | 1:47.50 | |
| 6 | 1:48.90 | 2 | 1:48.53 | |
| 7 | 1:50.18 | 8 | 1:48.98 | |
| 8 | 1:48.86 | 1 | 1:50.04 | |
| 9 | 1:50.57 | 9 | ||
| 10 | 1:50.88 | 10 | ||
| 11 | 1:51.20 | 11 | ||