To investigate the importance of arterial integrity in tibial fracture healing, the authors retrospectively assessed prognosis as a function of arterial injury in a large series of tibial fracture patients. The records of 114 patients who were treated for an open fracture of the tibia at a San Francisco hospital between 1981 and 1991 were selected for review; in each case, the injury had been caused by a blunt trauma, and arteriography had been performed to evaluate a suspected arterial injury in the ipsilateral extremity. Sixty-two patients had had a normal arteriogram and 52 had demonstrated occlusion of one or two of the three arteries that supply the foot. The group of patients who had demonstrated arterial occlusion had a significantly greater incidence of delayed union or nonunion (24 of 52 compared with ten of 62) and notably more cases of osteomyelitis (nine of 52 compared with four of 62); when the patients with osteomyelitis are excluded, the difference between the groups is still significant. This study is the first that indicates that patients with open fractures of the tibia who demonstrate arterial occlusion in their ipsilateral extremity may be more prone to delayed union or nonunion. More vigilant follow-up evaluation may therefore be warranted in such patients to better anticipate the need for exchange rodding or bone grafting.