The women's 4 × 400 metres relay event at the 2003 Pan American Games was held on August 9.
Results edit
| Rank | Nation | Athletes | Time | Notes |
|---|---|---|---|---|
 |
 United States |
Me'Lisa Barber, Moushaumi Robinson, Julian Clay, DeeDee Trotter | 3:26.40 | |
 |
 Jamaica |
Naleya Downer, Michelle Burgher, Novlene Williams, Allison Beckford | 3:27.34 | |
 |
 Brazil |
Maria Laura Almirão, Josiane Tito, Geisa Coutinho, Lucimar Teodoro | 3:28.07 | |
| 4 |  Mexico |
Liliana Allen, Mayra González, Gabriela Medina, Ana Guevara | 3:28.23 | NR |
| 5 |  Cuba |
Libania Grenot, Yanelis Lara, Yudalis Díaz, Adriana Muñoz | 3:28.79 | |
| 6 |  Puerto Rico |
Militza Castro, Yvonne Harrison, Sandra Moya, Yamelis Ortiz | 3:32.28 | |
| 7 |  Dominican Republic |
Yelmi Martínez, Jazmín Rodríguez, Claudia Rosa Vargas, Clara Hernández | 3:38.48 | NR |
 Colombia |
DQ |