We performed a prospective randomised trial on matched groups of patients with displaced tibial shaft fractures to compare conservative treatment with closed intramedullary nailing. The results showed conclusively that intramedullary nailing gave more rapid union with less malunion and shortening. Nailed patients had less time off work with a more predictable and rapid return to full function. We therefore consider that closed intramedullary nailing is the most efficient treatment for displaced fractures of the tibial shaft.