Swimming at the 2016 Summer Olympics – Women's 400 metre individual medley

The women's 400 metre individual medley event at the 2016 Summer Olympics took place on 6 August at the Olympic Aquatics Stadium.

Four years after narrowly missing the podium in London, Hungary's Katinka Hosszú, nicknamed the "Iron Lady", opened her redemptive Games by dominating the 400 m individual medley with a new world record and the first title of her Olympic career. Dominating the race from the very start, she pulled away from the field to a gold-medal finish with a 4:26.36. Hosszú's swim also demolished the world record of 4:28.43, set by China's Ye Shiwen at the previous Games. Trailing behind the leader by almost five seconds, U.S. swimmer Maya DiRado turned ahead of the world-record pace for over half the race, and managed to finish with a silver in 4:31.15. Meanwhile, Spain's Mireia Belmonte rounded out the podium with a bronze in 4:32.39, edging out Great Britain's Hannah Miley (4:32.54) in a tight battle to fourth by 0.15 of a second.

Canada's Emily Overholt finished fifth with a 4:34.70, and was shortly followed by London 2012 runner-up Elizabeth Beisel of the United States (4:34.98). Miley's teammate Aimee Willmott (4:35.04) and Japan's Sakiko Shimizu (4:38.06) rounded out the finale.

Reigning Olympic champion Ye Shiwen missed a chance to defend her title in the final, after finishing twenty-seventh out of thirty-three swimmers in the prelims.