Yes, Muhammad Ali lost five professional bouts during his boxing career. His first loss came on March 8, 1971, when he lost to Joe Frazier, the reigning heavyweight champion at the time. Ali’s third fight after his return to the sport following his ban for refusing to fight in the Vietnam War, it was billed as the “Fight of the Century.” Frazier won a unanimous 15-round decision. He next lost on March 31, 1973, to a little-known fighter named Ken Norton, who broke Ali’s jaw in the second round en route to a 12-round upset decision.
Ali’s final three losses occurred well after his athletic peak. In 1978 he lost to Leon Spinks, a novice boxer with an Olympic gold medal but only seven professional fights to his credit. Ali retired later that year, but two years later he made an ill-advised comeback and suffered a horrible beating at the hands of Larry Holmes in a bout that was stopped after 11 rounds. The final ring contest of Ali’s career was a loss by decision to Trevor Berbick in 1981. His final career record was 56 wins and 5 losses with 37 knockouts