Fifty consecutive comminuted fractures of the femoral shaft were treated by closed unlocked intramedullary nailing. Twelve unstable fractures also had cast-bracing. There were no cases of infection or non-union, and satisfactory results were achieved in 38 fractures (76%). More severe comminution led to a higher incidence of unsatisfactory results, but malrotation deformity was seen more often in less comminuted fractures and appeared to be due to poor operative reduction. Shortening in severe comminution was the main complication and was not controlled by supplementary cast-bracing. Closed unlocked intramedullary nailing is effective for lesser grades of comminution, but fractures with no cortical continuity at reduction should be treated with a locking nail.