The men's marathon at the 1968 Summer Olympics in Mexico City, Mexico, was held on Sunday October 20, 1968. The race started at 15:00h local time. There were 75 competitors from 41 countries. Eighteen of them did not finish. The maximum number of athletes per nation had been set at 3 since the 1930 Olympic Congress. The event was won by Mamo Wolde of Ethiopia, the nation's third consecutive gold medal in the Olympic marathon (matching France for most golds overall in the event).