Cowens retired as a player in 1980, as Boston drafted Kevin McHale and traded for Robert Parish to replace him at center. Boston then won the 1981 NBA Championship. "I have sprained my ankle at least 30 times over the duration of my career, broken both legs and fractured a foot," Cowens said upon retiring. "Two years ago, a team of foot and bone specialists said they were amazed that I could play up to that point without sustaining serious injuries."