| Final | Team | time | | L | | 1. Ana Guevara |  MEX | 50.34s | SB | 4 | | 2. Christine Amertil |  BAH | 50.99s | SB | 2 | | 3. Indira Terrero |  CUB | 51.09s | | 6 | | 4. Shereefa Lloyd |  JAM | 51.19s | | 3 | | 5. Davita Prendergast | JAM | 51.90s | | 5 | | 6. Monique Henderson |  USA | 52.28s | | 1 | | 7. LaVerne Jones |  ISV | 52.97s | | 7 | | 8. Debbie Dunn | USA | 52.97s | | 8 |
|
| World Record: | | Marita Koch (GDR) 47.60s | | Canberra (AUS) 06.10.1985 | | Panamerican Record: | | Ana Fidelia Quirot (CUB) 49.61s | | La Habana (CUB) 05.08.1991 |
|
| Heats - First 2 and Best 2 progress. |
| Heat 1. | Team | time | | | | 1. Ana Guevara | MEX | 51.10s | | | 7. LaVerne Jones | ISV | 51.94s | PB | | 8. Monique Henderson | USA | 52.18s | | | 11.Maria Laura Almirão | BRA | 52.72s | | | 12.Esther Akinsulie | CAN | 52.77s | | | 20.Lucy Jaramillo | ECU | 54.55s | | | -. Dominique Maloney | BVI | DQ | |
|
| Heat 2. | Team | time | | | | 2. Davita Prendergast | JAM | 51.47s | | | 3. Indira Terrero | CUB | 51.56s | | | 6. Debbie Dunn | USA | 51.86s | | | 10.Kineke Alexander | SVG | 52.37s | | | 14.Ginou Etienne | HAI | 53.13s | | | 17.María Idrobo | COL | 54.29s | | | 21.Hazel Ann Regis | GRE | 54.75s | |
|
| Heat 3. | Team | time | | | | 4. Shereefa Lloyd | JAM | 51.66s | | | 5. Christine Amertil | BAH | 51.67s | SB | | 9. Gabriela Medina | MEX | 52.22s | | | 13.Aliann Pompey | GUY | 53.03s | | | 15.Carline Muir | CAN | 53.25s | | | 16.Nathandra John | SKN | 53.42s | | | 18.Sheila Ferreira | BRA | 54.44s | | | 19.Britney St. Louis | TRI | 54.45s | |
|
|
| 