In this prospective study of ice hockey injuries in Finland we have investigated the incidence of injury at two playing levels and the causal factors, mechanisms, types, and consequences of the injuries. Seven Finnish ice hockey teams were observed during the 1988 to 1989 season. There were a total of 189 injuries. There were 134 injuries in 4 teams of the highest level, the Finnish National League, and 55 injuries in 3 teams of the second highest level, Division I. The incidence of injuries during games was 66 per 1000 player-game hours in the National League and 36 per 1000 player-game hours in Division I. As for severity, 10 (5%) injuries were classified as major. Of all injuries, 15 (8%) were fractures and 34 (18%) were to the head or face. The most severe injuries were tears of a knee ligament or fractures of an upper extremity. Ongoing surveillance and an exact reporting system are needed for establishing the trends in the number and severity of the injuries.