Athletics at the 1996 Summer Olympics – Men's 400 metres

The men's 400 metres event at the 1996 Summer Olympics in Atlanta, Georgia took place between 26 and 29 July. There were 62 competitors from 42 countries. The maximum number of athletes per nation had been set at 3 since the 1930 Olympic Congress.

The event was won by Michael Johnson of the United States. A few days later, Johnson would become the only man to win both the 400 metres and the 200 metres in the same Olympics. Johnson's 400 metres victory in Atlanta was the first of his two wins; he would become the only man to repeat as gold medalist in the event when he won again in 2000. More generally, his win was the fourth in what would ultimately be 7 consecutive American victories stretching from 1984 to 2008 and the 16th overall title in the event by the United States. Roger Black's silver medal was Great Britain's first in the event since 1936; Davis Kamoga's bronze was Uganda's first in the event ever.