Exposure of the prosthesis is one of the problems encountered after arthroplasty of the knee. Eight patients with nine exposed prostheses have been treated by using a gastrocnemius myocutaneous flap to provide cover. This preserved the prosthesis and closed the joint in six of the eight patients.l The factors leading to breakdown of the wound are discussed and the anatomy of the gastrocnemius myocutaneous flap and the operative procedure are described.