To determine function and complications after reverse total shoulder arthroplasty (RTSA) in obese patients compared with a control group of nonobese patients. Between 2005 and 2011, we performed 76 RTSAs in 17 obese, 36 overweight, and 23 normal weight patients, based on World Health Organization body mass index classification. We reviewed the charts for age, sex, body mass index, date of surgery, type of implant, type of incision, length of stay, comorbidities, surgical time, blood loss, American Society of Anesthesiologists score, shoulder motion, scapular notching, and postoperative complications. Complications and outcomes were analyzed and compared between groups. Reverse total shoulder arthroplasty in obese patients was associated with significant improvement in range of motion. Complication rate was significantly greater in the obese group (35%), compared with 4% in the normal weight group. We found no significant differences between scapular notching, surgical time, length of hospitalization, humeral component loosening, postoperative abduction, forward flexion, internal and external rotation, pain relief, or instability between groups. Our results show that obese patients have significant improvement in motion after RTSA but are at an increased risk for complication. Obesity is not a contraindication to RTSA, but obese patients need to understand fully the increased risk of complication with RTSA. Therapeutic III.