A total of 432 Danish competitive swimmers were asked to complete a questionnaire about the epidemiology of injuries sustained during swimming in the season of 1986/1987. Two hundred and sixty-eight (62%) replied. We found a total of 100 injuries in 80 swimmers with an incidence of 0.9 injuries per swimmer per 1,000 hours of swimming, and a point prevalence of 15% on the day of competition. The shoulder, the back and the knee joint were most commonly involved. No particular swimmingstroke was associated with a greater risk of injury. There was, however, a tendency for butterfly swimmers to have more frequent shoulder injuries and for breaststroke swimmers to have more frequent knee-injuries. Medal winners were significantly more frequently injured. Half of the injured swimmers were seen by a doctor.