Forty-two patients (65 shoulders) with osteonecrosis of the humeral head were reviewed. Minimal follow-up was 2 years or until shoulder arthroplasty was performed for persistent severe pain and disability not responsive to conservative treatment. Thirteen shoulders had surgery shortly after presentation, whereas 22 others initially treated conservatively required surgery. Thirty shoulders in 20 patients have been treated without surgery and were evaluated at an average of 10 years after initial presentation. Fifteen shoulders are doing satisfactorily, whereas 15 others are doing poorly. Overall, 37 (71%) shoulders had clinical progression of disease requiring shoulder arthroplasty or resulting in severe pain and disability. All had radiographic stage III, IV, or V, and 41 (85%) had articular surface incongruity of 2 mm or greater. Humeral head drilling was not effective in preventing clinical or radiographic progression in stage III.disease. Radiographic stages of III or greater and documented radiographic disease progression were significantly associated with a poor outcome.