A prospective study was performed to determine whether compartment pressures of the leg were affected by intramedullary fixation of the tibia. Ten of the 11 patients studied had surgery for acute diaphyseal fractures and 1 for tibial nonunion. Compartment pressures were measured immediately prior to the procedure and at 12 hours after the procedure. There was no difference between the preoperative and postoperative compartment pressures. Our data suggest that intramedullary stabilization of the tibia does not predictably increase compartment pressures.