The men's 4 × 100 meters relay was a track and field athletics event held as part of the Athletics at the 1912 Summer Olympics program. It was the debut of the event, which along with the 4 × 400-meter relays marked the first relays of equal legs in the athletics program (a medley relay had been held in 1908). The competition was held on Monday, July 8, 1912, and on Tuesday, July 9, 1912. NOCs could enter 1 team of 4 athletes, with up to 2 reserves.