Event Format: Swimmers competed in preliminary heats, final and B-final. In the preliminary heats the swimmers with the best official starting times were placed in the last three heats. Normally eight swimmers competed in each heat. The eight swimmers with the best time in the preliminary heats advanced to the final. Swimmers placing 9th to 16th advanced to the B-final. The winner of the final was the Olympic Champion.
Event facts: Women's 400 m freestyle competition was held at the Piscines Bernat Picornell and 33 athletes participated in the event.