BACKGROUND: Hemiarthroplasty is a common treatment for cuff tear arthropathy and glenohumeral arthritis associated with a massive tear of the rotator cuff; however, to our knowledge, long-term outcomes and preoperative factors affecting results have not been reported. METHODS: Thirty-four shoulders in thirty-one patients with cuff tear arthropathy or a massive rotator cuff tear with glenohumeral arthritis underwent hemiarthroplasty at an average age of seventy-two years. Outcomes in all patients were evaluated by direct physical examination and according to the limited goals criteria of Neer et al. at a mean of 3.7 years postoperatively. In twenty-five shoulders, long-term outcomes were measured with use of the American Shoulder and Elbow Surgeons (ASES) scoring system and follow-up data were obtained at a mean of ten years (range, four to sixteen years) postoperatively. RESULTS: Twenty-six of thirty-four shoulders satisfied the limited goals criteria described by Neer et al. The mean active forward elevation improved from 78 degrees preoperatively to 111 degrees postoperatively (p < 0.001). The mean active external rotation improved from 15 degrees preoperatively to 38 degrees postoperatively (p < 0.0001). One patient with a history of four failed rotator cuff repairs had anterosuperior instability develop after surgery. The mean final total ASES score was 67 points (range, 35 to 100 points). Of the sixteen shoulders in patients who could actively elevate the arm to >= 90 degrees preoperatively, fourteen achieved satisfactory results according to the limited goals criteria of Neer et al. Patients who could actively elevate the arm to 900 had significantly better function (mean ASES function score, 31 compared with 23 points; p = 0.05), pain relief (mean ASES pain score, 48 compared with 30 points; p = 0.002), and higher total ASES scores (mean, 80 compared with 54 points; p < 0.001) than the patients who were unable to actively elevate the arm to 90 degrees. CONCLUSIONS: Hemiarthroplasty can provide good long-term results in rotator cuff-deficient patients with glenohumeral arthritis. Patients who have preoperative forward elevation of >= 90 degrees benefit the most. A low complication rate can be expected for this procedure. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.