During the spring of 2001, 1975 children, from grades 3, 6 and 9 participated in a nationwide, multidisciplinary collaboration study. The students came from randomly selected classes throughout Sweden, representing different geographical and socio-economic areas. The aim of this study was to collect and evaluate self-reported injuries and associated factors during various physical activities as recalled retrospectively for 3 months by the students. Every sixth student (n=299 or 16%) reported 306 injuries. Twice as many girls than boys were injured during physical education class. Ninth-grade students reported relatively more injuries during organized sports than during physical education class and leisure activities. There were no age or gender differences in incidence rate during leisure activities. Most injuries were minor, as 70% were back in physical activity within a week. Half of the students (50%) reported that they previously had injured the same body part. Primary care of the injured student was, with the exception of a family member, most often carried out by the physical education teacher or coach, which accentuates the importance of continuous sports medicine first aid education for this group.