Athletics at the 1968 Summer Olympics – Men's 100 metres

This was the sixteenth time the event was held, having appeared at every Olympics since the first in 1896. The gold medalist from 1964, American Bob Hayes, did not return (playing in the National Football League instead), but Tokyo silver medalist Cuban Enrique Figuerola and bronze medalist Canadian Harry Jerome did. The American team was lead by Jim Hines and Charles Greene, two of the three men to establish the world record at 9.9 seconds during the Night of Speed; Mel Pender, a 1964 finalist, was the third member of the team. Jamaican Lennox Miller was the strongest challenger to the Americans.[2]

El Salvador, Nicaragua, Puerto Rico, Suriname, and Tanzania were represented in the event for the first time. East and West Germany also competed separately for the first time. The United States was the only nation to have appeared at each of the first sixteen Olympic men's 100 metres events.

The event retained the same basic four round format from 1920–1964: heats, quarterfinals, semifinals, and a final. A significant change, however, was the introduction of the "fastest loser" system. Previously, advancement depended solely on the runners' place in their heat. The 1968 competition added advancement places to the fastest runners across the heats in the first round who did not advance based on place.

The first round consisted of nine heats, most with 7–8 athletes but the first having only 5. The top three runners in each heat advanced, along with the next five fastest runners overall. This made 32 quarterfinalists, who were divided into four heats of 8 runners. The top four runners in each quarterfinal advanced (with no "fastest loser" provision in rounds after the first). The 16 semifinalists competed in two heats of 8, with the top four in each semifinal advancing to the eight-man final.[2][3]

Prior to the competition, the existing World and Olympic records were as follows.

World record	9.9	Jim Hines	Sacramento, United States	20 June 1968
	9.9	Ronnie Ray Smith	Sacramento, United States	20 June 1968
	9.9	Charles Greene	Sacramento, United States	20 June 1968
Olympic record	10.0	Bob Hayes	Tokyo, Japan	15 October 1964

Jim Hines had a time of 9.9 seconds (hand-timed) or 9.95 seconds (auto-timed) in the final. This equalled the world record and set a new Olympic record, which were measured by hand-timing at that point. The 9.95 second time was recognized as the initial world record for electronic timed results when the IAAF changed its records rules in 1977.