| Date | 18 October 1968 |
|---|---|
| Location | Alberca Olímpica Francisco Márquez, Ciudad de México |
| Pos | Lane | Competitor | NOC | Time | |||
|---|---|---|---|---|---|---|---|
| 1 | 4 | Luis Nicolao |  ARG | 54.6 | |||
| 2 | 3 | Bobby McGregor |  GBR | 55.1 | |||
| 3 | 2 | Greg Rogers |  AUS | 55.4 | |||
| 4 | 7 | José Roberto Aranha |  BRA | 56.8 | |||
| 5 | 5 | Mario Santibáñez |  MEX | 57.0 | |||
| 6 | 1 | Andrew Loh |  HKG | 1:00.7 | |||
| 7 | 6 | Luis Aguilar |  CRC | 1:04.5 |
