Swimming at the 2005 World Aquatics Championships – Women's 400 metre freestyle

The Women's 400 Freestyle at the 11th FINA World Aquatics Championships was swum on 24 July 2005 in Montreal, Quebec, Canada. Preliminary heats were swum that morning, with the top-8 finishers advancing to swim the race again in that evenings Final.

As the competition was held in a long course (50m) pool, the race consisted of 8 lengths of freestyle.

At the start of the event, the existing World (WR) and Championships (CR) records were:
 * WR: 4:03.85, Janet Evans (USA), swum 22 September 1988 in Seoul, South Korea;
 * CR: 4:06.28, Tracey Wickham (Australia), swum 24 August 1978 in Berlin, Germany.