The women's 400 metre freestyle event at the 2004 Olympic Games was contested at the Olympic Aquatic Centre of the Athens Olympic Sports Complex in Athens, Greece on August 15.

[1] France's Laure Manaudou won the gold medal in this event, with a European record time of 4:05.34.

The silver medal was awarded to Poland's Otylia Jędrzejczak, who finished behind Manaudou by half a second (0.50), in an outstanding time of 4:05.84.

U.S. swimmer Kaitlin Sandeno, who earned a silver in the 400 m individual medley on the previous day, fought off a challenge from Romania's Camelia Potec in the final lap to take a bronze by two tenths of a second (0.20), clocking at 4:06.19.

[2][3] Prior to this competition, the existing world and Olympic records were as follows.