Nineteen shoulder arthroplasties for the treatment of nontraumatic avascular necrosis of the humeral head were evaluated. The osteonecrosis was idiopathic in 6 shoulders, was a result of corticotherapy in 10, occurred after radiation in 2, and occurred after Gaucher's disease in 1. A total shoulder arthroplasty was performed in 5 cases and a hemiarthroplasty in 14. At 7 years' follow-up (range, 2 to 12 years), there were 7 excellent, 9 satisfactory, and 3 unsatisfactory results. The Constant score averaged 58 points, for an adjusted score of 78%. Radiolucent lines were present around 2 glenoid components, and 1 was radiographically loose. In 2 cases with humeral head replacement, there was painful glenoid wear. Shoulder arthroplasty for nontraumatic avascular necrosis yields satisfactory results with a pain-free shoulder in more than 80% of cases. However, limitation of motion often persists. Better results can be expected with shorter preoperative delay, when preoperative pain is moderate and range of motion preserved and when the etiology is not postradiation avascular necrosis, which in our series yielded the worst results.