Swimming at the 2000 Summer Olympics – Women's 400 metre freestyle

The women's 400 metre freestyle event at the 2000 Summer Olympics took place on 17 September at the Sydney International Aquatic Centre in Sydney, Australia.

Brooke Bennett emerged as a major force in long-distance swimming, after effortlessly winning a first gold for the United States in the event since Janet Evans did so in 1988. She maintained a powerful lead from start to finish, and posted a lifetime best of 4:05.80, making her the third fastest all-time swimmer in history behind Evans and China's Chen Hua. At only 18 years of age, Diana Munz fought off a sprint challenge from Costa Rica's Claudia Poll and Jamaica's Janelle Atkinson on the final lap to take home the silver in 4:07.07, extending a distance swimming legacy for the Americans with a one–two finish. Meanwhile, Poll settled only for the bronze in 4:07.83.

Atkinson made an Olympic milestone as the first Jamaican to reach a swimming final, but missed out the podium by almost a full second in a national record of 4:08.79. Russia's Nadezhda Chemezova finished fifth in 4:10.37, holding off a fast-pacing Hannah Stockbauer of Germany (4:10.38) by a hundredth of a second (0.01). Netherlands' Carla Geurts (4:12.36), and China's Chen Hua (4:13.11), the second fastest all-time swimmer, rounded out the finale.