Forty-three high energy open tibial diaphyseal fractures were treated with unreamed locked intramedullary nails from 1989 to 1992, and were reviewed at a minimum of 1 year from injury. There were 6 Grade I, 2 Grade II, 16 Grade IIIA, 9 Grade IIIB, and 1 Grade IIIC open fractures. Ninety-eight percent of the fractures united in an average time of 6.1 months. However, 47% of the fractures required an additional procedure before union. Complications included 49% of fractures with malunions, 12% deep infections, 41% locking screw breakages, and 20% compartment syndromes. These results are similar to those achieved with external fixation of open tibial fractures. The unreamed locked intramedullary nail has not improved the outcome of open tibial diaphyseal fractures because the biologic consequences of the injury are of greater significance than the methods or techniques of fracture stabilization.