The men's 66 kg tournament in judo at the 2008 Summer Olympics was held on August 10 at the Beijing Science and Technology University Gymnasium.

This event was the second-lightest of the men's judo weight classes, limiting competitors to a maximum of 66 kilograms of body mass.

If the bout was still tied at the end, it was extended for another five-minute, sudden-death period; if neither judoka scored during that period, the match is decided by the judges.

The tournament bracket consisted of a single-elimination contest culminating in a gold medal match.

The two judokas who lost in the semifinals faced the winner of the opposite half of the bracket's repechage in bronze medal bouts.