10 patients with previous femoral shaft fracture treated with locked intramedullary nailing were examined by computed tomography (CT) a few days after nail removal. The bone density, cortical thickness and geometric shape of the fractured extremity were compared with those on the contralateral side. Only a small reduction in cortical density and thickness (4 and 7 percent, respectively) was revealed outside the fracture area in the diaphyseal part of the nailed bones. A distinct reduction in trabecular density was observed in the femoral condyles as well as in the ipsilateral tibial condyle (19 and 17 percent, respectively). Our results indicate that the stress-reducing effect of intramedullary nails on the femoral diaphysis is small.