The men's 100 metre freestyle event at the 1964 Olympic Games took place between October 11 and 12.

Great Britain (Bobby McGregor's silver) and the United Team of Germany (Hans-Joachim Klein's bronze) both earned their first medal in the men's 100 metre freestyle.

John Devitt of Australia, the winner of a controversial finish in 1960, had retired, as had silver medalist Lance Larson of the United States.

The American team in Tokyo was led by Don Schollander, who was expected to vie with Scotsman Bobby McGregor.

[2] Iran, Puerto Rico, South Korea, and Thailand each made their debut in the event.

The officials used unofficial electronic scoring to determine which swimmer won the bronze medal - Klein had finished one one-thousandth of a second sooner than Ilman.