The men's 100 metre freestyle event at the 1984 Summer Olympics was held in the McDonald's Olympic Swim Stadium in Los Angeles, California, on July 31, 1984. There were 68 competitors from 45 nations. Nations were limited to two swimmers each, down from three in prior Games. The event was won by Rowdy Gaines of the United States, the nation's third victory in four Games—with only the boycotted 1980 Olympics missing. Overall, it was the eleventh victory for an American in the men's 100 metre freestyle, most of any nation. Mark Stockwell of Australia took silver. Swedish swimmer Per Johansson repeated as bronze medalist, only the seventh man to earn multiple medals in the event.