Forty-eight shoulders with glenohumeral osteoarthritis were treated by hemireplacement arthroplasty with a Vitallium humeral-head prosthesis in forty-seven patients, twenty-nine of whom were women. The results in an average follow-up of six years (range, one to twenty years) showed relief of pain and restoration of good function in nearly all patients. Recovery of adequate strength was slow, and continued fatigability was noted by some. Total shoulder-joint surface replacement was performed in one patient in this series with good early results.