BACKGROUND Many patients with rheumatoid arthritis develop superior migration of the humeral head because of massive cuff tears, causing loss of active motion. Reverse shoulder arthroplasty could potentially restore biomechanical balance but a high incidence of glenoid failure has been reported. These studies do not, however, typically include many patients with rheumatoid arthritis (RA) and it is unclear whether the failure rates are similar. OBJECTIVE We therefore (1) evaluated pain relief and shoulder function after reverse arthroplasty in RA; (2) compared results between primary and revision procedures; (3) determined the incidence of scapular notching; and (4) determined the complication rate. METHODS We identified 29 patients with RA who had 33 reverse arthroplasties from among 412 patients having the surgery. Six patients were lost to followup. Twenty three patients (27 shoulders) were evaluated after a minimum followup of 18 months (mean, 56 months; range, 18-143 months), including 18 primary and nine revision arthroplasties. All patients were evaluated preoperatively and 23 shoulders postoperatively by an independent physiotherapist and four were assessed postoperatively by phone. Level of pain, range of motion, and Constant-Murley score were recorded and new radiographs taken. RESULTS Visual Analog Scale score for pain decreased from 8.0 to 1.0. Constant-Murley score increased from 13 to 52. Primary procedures had higher scores compared with revisions. Three patients had revision surgery. Notching occurred in 52% of shoulders but no loosening was seen. CONCLUSIONS Reverse arthroplasty in rheumatoid arthritis improved shoulder function with a low incidence of complications. We believe it should be considered in elderly patients with rheumatoid arthritis with pain and poor active range of motion resulting from massive cuff tears. METHODS Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.