Overuse injuries, and stress fractures in particular, afflict many runners and military recruits. This investigation sought to identify pretraining factors which may predispose to overuse injuries. Orthopedic and running history questionnaires and an orthopedic examination were administered to 505 trainees entering an intensive military training school. A novel method for evaluating ankle dorsiflexion was developed, and alignment measures, in units of centimeters rather than degrees, were obtained. Over 10% of the trainees were removed from the school for overuse-related injuries, and over half of these were tibial stress fractures. The incidence of clinically diagnosed stress fractures was 6.3%. No single orthopedic history question or combination of questions could discriminate between trainees who did or did not subsequently incur overuse injuries. Results from the running history indicated that those running 25 or more miles.wk-1 (mpw) had a significantly (P less than 0.027) lower incidence of stress fractures (3.0%) than those running 4 or fewer mpw over the previous year (11.5%). The orthopedic examination did not identify any predisposing alignment characteristics, perhaps due to the low incidence of overuse injuries. Population means are presented for future use in comparative studies.