| Semifinal - 22.08.04 | | Heat 1 | Team | Time | | 1. Ana Guevara | Mex | 50.15s | | 2. Christine Amertil | Bah | 50.17s PB | | 3. Sanya Richards | USA | 50.54s | | 4. Christine Ohurougu | Gbr | 51.00s | | 5. Tiandra Ponteen | Skn | 51.33s | | 6. Svetlana Usovich | Blr | 51.42s | | 7. Hazel-Ann Regis | Grn | 51.47s | | 8. Egle Uljas | Est | 53.13s | | Heat 2 | Team | Time | | 1. Tonique Williams-Darling | Bah | 50.00s | | 2. DeeDee Trotter | USA | 50.14s PB | | 3. Natalya Nazarova | Rus | 50.63s | | 4. Fatou Bintou Fall | Sen | 51.21s | | 5. Kaltouma Nadjina | Cha | 51.57s | | 6. Estie Wittstock | Rsa | 51.77s | | 7. Donna Fraser | Gbr | 51.94s | | 8. Grazyna Prokopek | Pol | 51.96s | | Heat 3 | Team | Time | | 1. Monique Hennagan | USA | 49.88s | | 2. Natalya Antyukh | Rus | 50.04s | | 3. Novlene Williams | Jam | 50.85s | | 4. Mariyana Dimitrova | Bgr | 51.20s EPB | | 5. Aliann Pompey | Guy | 51.61s | | 6. Antonina Yefremova | Ukr | 51.90s | | 7. Mireille Nguimgo | Cmr | 52.21s | | 8. Lee McConnell | Gbr | 52.63s |
| | Round 1 - 21.08.04 | | Heat 1 | Team | Time | | 1. Ana Guevara | Mex | 50.93s | | 2. Lee McConnell | Gbr | 51.19s | | 3. Grazyna Prokopek | Pol | 51.29s PB | | 4. Fatou Bintou Fall | Sen | 51.87s | | 5. Hortense Bewouda | Cmr | 52.11s | | 6. Oksana Luneva | Kir | 52.94s | | 7. Ruwida El Hubti | Lba | 1:03.57s NR | | Heat 2 | Team | Time | | 1. Monique Hennagan | USA | 51.02s | | 2. Mariyana Dimitrova | Bgr | 51.29s | | 3. Kaltouma Nadjina | Cha | 51.50s | | 4. Nadia Davy | Jam | 52.04s | | 5. Maria Laura Almirao | Bra | 52.10s | | 6. Kirsi Mykkanen | Fin | 52.53s | | 7. Fanfang Bo | Chn | 56.01s | | Heat 3 | Team | Time | | 1. Natalya Nazarova | Rus | 50.82s | | 2. Donna Fraser | Gbr | 51.19s | | 3. Hazel-Ann Regis | Grn | 51.66s | | 4. Estie Wittstock | Rsa | 51.89s | | 5. Amy Mbacke Thiam | Sen | 52.44s | | 6. Amantle Montsho | Bot | 53.77s NR | | 7. Zamira Amirova | Uzb | 54.43s | | Heat 4 | Team | Time | | 1. Natalya Antyukh | Rus | 50.54s | | 2. DeeDee Trotter | USA | 50.56s | | 3. Novlene Williams | Jam | 50.59s PB | | 4. Aliann Pompey | Guy | 51.33s | | 5. Egle Uljas | Est | 51.91s NR | | 6. Svetlana Bodritskaya | Kaz | 53.35s | | 7. Shifana Ali | Mdv | 1:00.92s NR | | Heat 5 | Team | Time | | 1. Tonique Williams-Darling | Bah | 51.20s | | 2. Svetlana Usovich | Blr | 51.37s | | 3. Antonina Yefremova | Ukr | 51.53s | | 4. Mireille Nguimgo | Cmr | 51.90s | | 5. Allison Beckford | Jam | 52.85s | | 6. Sandrine Thiebaud-Kangni | Tog | 52.87s | | 7. K V Damayanthi Dharsha | Sri | 54.58s | | Heat 6 | Team | Time | | 1. Sanya Richards | USA | 50.11s | | 2. Christine Amertil | Bah | 50.23s PB | | 3. Christine Ohurougu | Gbr | 50.50s PB | | 4. Tiandra Ponteen | Skn | 51.17s | | 5. Geisa Aparecida Coutinho | Bra | 52.18s | | 6. Makelesi Bulikiobo | Fij | 53.58s | | 7. Salamtou Hassane | Ngr | 1:03.28s NR |
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