Athletics at the 1984 Summer Olympics – Men's 100 metres

This was the twentieth time the event was held, having appeared at every Olympics since the first in 1896. Defending gold medal winner Allan Wells of Great Britain was the only finalist from the Moscow Games to return. The American team was strong, led by 1983 World Championships in Athletics winner Carl Lewis, who was attempting to match Jesse Owens's 1936 quaduple (100, 200, 4x100, and long jump). Sam Graddy and Ron Brown were the other members of the United States squad, edging out world record holder and World Championships runner-up Calvin Smith. Challengers to the hosts included World Championship finalists Wells, Paul Narracott of Australia, Christian Haas of West Germany, and Desai Williams of Canada, as well as up-and-coming Canadian sprinter Ben Johnson.[2]

Thirteen nations appeared in the event for the first time: Antigua and Barbuda, Bangladesh, the British Virgin Islands, China (in its People's Republic form), Costa Rica, Equatorial Guinea, The Gambia, Mauritius, Oman, Qatar, the Solomon Islands, Swaziland, and the United Arab Emirates. The United States made its 19th appearance in the event, most of any country, having missed only the boycotted 1980 Games.

The event retained the same basic four round format introduced in 1920: heats, quarterfinals, semifinals, and a final. The "fastest loser" system, introduced in 1968, was used again to ensure that the quarterfinals and subsequent rounds had exactly 8 runners per heat; this time, the system was used in both the preliminaries and quarterfinals.

The first round consisted of 11 heats, each with 7 or 8 athletes. The top three runners in each heat advanced, along with the next seven fastest runners overall. This made 40 quarterfinalists, who were divided into 5 heats of 8 runners. The top three runners in each quarterfinal advanced, with one "fastest loser" place. The 16 semifinalists competed in two heats of 8, with the top four in each semifinal advancing to the eight-man final.[2][3]

These are the standing world and Olympic records (in seconds) prior to the 1980 Summer Olympics.

World Record	9.93	Calvin Smith	Colorado Springs (United States)	July 3, 1983
Olympic Record	9.95	Jim Hines	Mexico City (Mexico)	October 14, 1968

• Athletics at the Friendship Games – Men's 100 metres