Schoolboy rugby injuries are a cause for concern in medical and non-medical circles, but few scientific investigations into their nature and frequency have been undertaken. We therefore decided to carry out a prospective study of the pattern of injuries occurring during one rugby season among boys in age groups ranging from under 10 to under 19 at one school, and to relate them to age, team level, time of season, position played and phase of play. Results showed that there are well-defined physical factors and conditions of play most likely to cause injury, and suggestions are made as to how these injuries could be minimized.