During one 18-week season, in which players from 26 high schools played 3,350 rugby matches, 495 injuries prevented players from participating in rugby for at least 1 week; 71% occurred during matches and 29% during practices. Injury was more common during the first 4 weeks of the season and again in the same time period after the mid-season vacation. At all ages, A-team players suffered the greatest number of injuries. The safest playing positions were tight-forward and scrum-half; the most dangerous loose-forward and in the back-line excluding the scrum-half. Overall, eightmen were the most often injured players. Of all injuries 55% occurred while the player was tackling or being tackled and 18% during the loose scrum/maul. The lower limb (37%), the head and neck (29%) and the upper limb (20%) were most commonly injured, and fractures (27%), ligament/tendon injuries (25%) and muscle injuries (17%) were commonest. However, concussion injuries were underreported in 19 of the 26 schools. This study shows: that monitoring rugby injuries through correspondence results in underreporting of injuries; that rugby injuries show specific trends with age, team level, playing position, time of the season and phase of play; and that players in the different positions suffer specific injuries in predictable phases of the game. Speed of play may be the most important aetiological factor in the majority of rugby injuries.