We investigated the frequency, cause and location of injuries in Icelandic elite soccer in 1991. The incidence of injuries for the individual player was 34.8 +/- 5.7 per 1000 game-hours and 5.9 +/- 1.1 per 1000 practice-hours. The most common types of injuries were muscle strains (29%), ligament sprains (22%), contusions (20%), and other injuries (29%). The frequency of reinjury was markedly high, where 44% of the strains and 58% of the sprains were registered as reinjuries. Strains occurred mainly during sprinting, sprains by tackling, and contusion during other contact. Significantly more injuries occurred on artificial turf than on grass or gravel in correlation to number of hours in games and practices. Teams who had the longest pre-season preparation period obtained significantly fewer injuries during the season.