Overuse injuries represent the largest percentage of sports-related injuries requiring medical treatment. These injuries represent a substantial health issue for the millions of adults who have made physical activity an integral part of their lifestyle, but may be even more important to those pursuing ultraendurance exercise. The purposes of this study were to report the type and incidence of overuse injuries in ultraendurance triathletes and to relate training practices to injury occurrence. Data was gathered from the responses of 95 competitors (75 men, 20 women) in the 1986 Hawaii Ironman Triathlon who completed a training and medical history questionnaire. In this sample, virtually all (91%) sustained at least one soft tissue, overuse injury during the previous year's training. The area of the body most frequently involved was the back, but the most common pattern was to have multiple areas involved. Because of the consistent combinations of injuries, mechanical abnormalities, such as diminished shock absorption, may have contributed to injury. Training habits were extremely variable and not directly related to either the incidence or type of injury.