Twenty-seven anatomical studies were done to elucidate the periosteal blood supply on the lateral surface of the shaft of the tibia. The dissection of a vascularised periosteal flap is described. The applications of this flap are discussed in the light of previous clinical and experimental reports on periosteal flaps and a successful clinical case is detailed. This flap has application for electively treating bony non union. It may also be used as a free flap in an acute trauma situation involving bone loss.