Most studies reporting on sports injuries have been investigations of specific types and locations in specific sports events and levels. This study aims at outlining the features of sports injuries in general regardless of type, severity, or treatment during 1 year among the adult population of the Greater Helsinki area (pop. 600,000). This study was carried out in cooperation with the Central Statistical Office, which in 1980 performed a nationwide survey aimed at outlining the incidence and features of accidents occurring in Finland. The actual data from this study concerning sports injuries in the Greater Helsinki area was broken down and further analyzed. During the actual time period under investigation, an estimated 40,380 acute sports injuries occurred in the area. Based on this estimate, the calculated occurrence of sports injuries was found to be 670 +/- 121/10,000 inhabitants. Sports injuries were found mainly among young people in their productive working years, though surprisingly low was the occurrence of injuries among women of 20-24 years of age. The majority of the injuries were of mild character, though 9% were classified as severe, and it was estimated on the basis of the data obtained from this study that some 4000 patients attended a casualty department in the area because of an injury sustained in sports, thus placing a considerable burden on these agencies. Distorsions formed with 65% the most common type of injury, and the application of an adhesive bandage was the commonest form of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)