The 400 metres hurdles at the World Championships in Athletics has been contested by women since 1980 and by men since 1983.
Karsten Warholm is the most successful athlete in the history of the event, winning three medals between 2017 and 2023. is the second most successful athlete, winning two gold medals and one silver medal between 2001 and 2007. Nezha Bidouane has the same medal tally as Sanchez and is the most successful female athlete, winning two golds and one silver between 1997 and 2001. Yuliya Pechonkina, Lashinda Demus and Dalilah Muhammad have won the most medals in the event, with four total; all won one gold, two silver and one bronze.
The United States is the most successful nation in the discipline, winning 7 gold medals in the men's discipline, 5 gold medals in the women's discipline and 39 medals in total. Great Britain is the only other nation that has won gold in both the men's and the women's event, winning gold in the women's event in 1993 and gold in the men's event in 2011.
The championship records for the event are 46.29 for men, set by Alison dos Santos in 2022, and 50.68 s for women, set by Sydney McLaughlin, also in 2022. The women's world record has been broken four times at the World Championships: by Sally Gunnell in 1993, Kim Batten in 1995, Dalilah Muhammad in 2019, and Sydney McLaughlin in 2022. The men's world record has never been broken at the competition.