Forty comminuted or unstable fractures of the femoral shaft were treated by closed intramedullary reaming and locked nailing. Twenty-four fractures were severely comminuted, and the other 16, in the distal or proximal third of the shaft, were classified as unstable. At 12 to 30 months postoperatively all the fractures had healed. Three patients had lateral rotation deformity of 5 degrees to 10 degrees, three had shortening of 1 to 2 cm and two had lengthening of about 1 cm. There were no infections or delayed unions. Closed intramedullary locked nailing can provide stability in fractures of the femoral shaft, irrespective of the degree of comminution and the site of injury.