400 metres at the World Athletics Championships

400 metres at the World Athletics Championships
Amantle Montsho and Allyson Felix at the finish of the 2011 women's final
Overview
Gender	Men and women
Years held	Men: 1983 – 2023 Women: 1983 – 2023
Championship record
Men	43.18 Michael Johnson (1999)
Women	47.99 Jarmila Kratochvílová (1983)
Reigning champion
Men	Antonio Watson (JAM)
Women	Marileidy Paulino (DOM)

The 400 metres at the World Championships in Athletics has been contested by both men and women since the inaugural edition in 1983. It is the second most prestigious title in the discipline after the 400 metres at the Olympics. The competition format typically has two or three qualifying rounds leading to a final between eight athletes.

The championship records for the event are 43.18 seconds for men, set by Michael Johnson in 1999, and 47.99 seconds for women, set by Jarmila Kratochvílová in 1983. The men's world record has been broken at the competition on one occasion and Johnson's championship record remains the world record as of 2015.^[1] The current women's championship record stood as the women's world record for two years and remains the only time that feat has been accomplished at the championships.

Michael Johnson is the most successful athlete of the World Championships 400 m, having won four straight titles from 1993 to 1999. He is the only sprint athlete to have won that many individual titles in an event. The second most successful is LaShawn Merritt – a two-time champion and the only other athlete to have won four medals. The most successful women are Marie-José Pérec, Cathy Freeman and Christine Ohuruogu, all of whom have won two world titles. Jeremy Wariner is the only other person to have won two titles, and also has three medals to his name.

The United States is comfortably the most successful nation in the discipline – American men have topped the podium ten times and taken 23 medals in total. American women also top the table with two golds among seven medals. Jamaica is the only other nation to have won more than one medal in the men's race, and has won eleven medals in total across the sexes. Great Britain has had two winners and two runners-up. Australia, France and Bahamas are the only other nations to have won multiple gold medals.

Jerome Young is the only athlete to be stripped of a medal in the event, as he lost his 2003 gold medal due to a doping ban.