A questionnaire was sent to all 960 entrants in a major city marathon race to obtain information on training-related injuries. A total of 497 replies were received; of these 287 (58%) had incurred some form of injury during preparation for the race. Seventy-one of these individuals reported more than one injury. Almost all injuries affected the lower limb, with 113 cases (32%) involving pain or disability in the knee. More than half the injured runners (158, 55%) sought no professional advice; approximately half (146, 51%) received no treatment other than rest, which was not generally considered a form of therapy. Only 18 runners (6%) reported no improvement in their condition, while 143 individuals (51%) reported a full recovery. Injury incurred during training was thought by 98 runners (35%) to have had an adverse effect on their racing performance. These results suggest that runners preparing to compete in marathon races can expect their training to be interrupted by injury.