The aggressiveness in top level soccer is increasing. The quality of refereeing is variable leading to games with increasing number of fouls. Two studies from Hawkins & Fuller (1996, 1998) showed that only 15-29% of injuries at international and elite level soccer resulted in foul play, whereas the rest of the injuries occurred where no foul play was adjudged by the referee to have taken place. In all these "non-foul" situations, in which injury resulted, at least 60% still involved player to player contact. Ekstrand & Gillquist (1983) found corresponding results in lower division male soccer showing that 23% of traumatic game injuries were caused by foul play. In modern soccer the number of fouls seems to be increasing. The impact of the referee on the number of faults and indirectly on the injury rate is therefore more important than previously. The role of the referee as an extrinsic risk factor of soccer injuries has so far never been studied. This project will focus on foul play, the adjudgment of the referee according to the current interpretation of the soccer rules in elite soccer. There may be a potential for reducing the injuries by educating the referees and players on following the rules of the game. In addition, analysis of called and non-called fouls may result in changes of the enforcement of todays rules in the game. Material and methods: All video tapes (182) from Norwegian elite division games in year 2000 will be assessed for the adjudgment of the referee when an injury or a high risk incident occur. A group of experienced referees will analyze the recordings and assess whether the decision taken by the referee was correct or not correct according to common interpretation of soccer rules. The findings may result in permanent alteration of the rules of soccer and may be employed to teach referees by using the guided discovery method presented by Ettlinger et al. (1995).