Studies on the incidence of soccer injuries have produced a variety of sometimes conflicting results. This may be explained by differences in the definition of soccer injury and the methods of data collection being used, and by selection mechanisms in the study populations. The incidence of injuries, therefore, depends on the population being studied. High risk groups exist with respect to age, gender and level of competition. Competition produces a higher risk of injury than practice, even when corrections for exposure time are made. The range of results of studies concerning different aspects of the severity of injuries may also be well explained by differences in the definition of injury, research methodology and selection with respect to age, gender, level of play and sociocultural background. In countries where soccer is very popular, the healthcare and social security systems are taxed considerably. On the other hand, soccer injuries appear to be no more serious than injuries resulting from other sports activities. A general conclusion is that the epidemiological information of the sport medical aspects of soccer injuries is inconsistent and far from complete. More research is needed to identify high risk groups and independent predictor variables of injury within those subgroups. Preferably, such studies should include uniform definitions of injury and should be based on sound epidemiological methodological principles.