The role of reverse shoulder arthroplasty (RTSA) in the relatively young individual is currently unclear. Our study evaluates the midterm to long-term results of RTSA for patients aged younger than 65 years with pseudoparalysis secondary to massive irreparable rotator cuff tears, with or without arthritis. Methods: Between 1997 and 2006, 46 RTSAs (41 patients) were performed. Mean age was 60 years (range, 46-64 years). At the latest follow-up, 5 patients had died and 1 was lost, leaving 35 patients (40 shoulders) with a mean follow-up of 93 months (range, 60-171 months). Results: The mean relative Constant score increased from 34 to 74 (P.4). Conclusion: RTSA in younger patients provides significant subjective improvement and substantial gain in overall function, which is maintained up to 10 years. Although the complication rate is high, most can be treated successfully without compromise to clinical outcome. However, it is imperative that the high complication rate is explained to patients, with the risks and benefits carefully considered. ? 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.