Athletics at the 1976 Summer Olympics – Men's 400 metres
The men's 400 metres was an event at the 1976 Summer Olympics in Montreal. The competition was held on July 26, 1976, July 28, 1976, and on July 29, 1976. Forty-four athletes from 29 nations competed. The maximum number of athletes per nation had been set at 3 since the 1930 Olympic Congress. The event was won by Alberto Juantorena of Cuba, the nation's first medal in the event, breaking a string of five victories by the United States. Juantorena became the first man to win both the 800 metres and 400 metres in an Olympics.