BACKGROUND: Proximal humerus fractures are quite common, constituting 5% of all fractures. Plate osteosynthesis of comminuted fractures in the elderly with osteoporotic bones is prone to complications, including loss of reduction, intraarticular protrusion of screws, avascular necrosis and non-union. Hemiarthroplasty may be preferred to achieve a stable fixation, which permits early shoulder motion. Prerequisites for the successful functional outcome of this surgical technique are to have an intact rotator cuff, which is often torn, and achieve proper soft tissue balance, which is technically demanding. In RSA design, deltoid muscle replaces the function of the supraspinatus, compensating for a dysfunctional rotator cuff or a displaced tuberculum. We designed a retrospective study to evaluate the results of proximal humerus fractures treated with reverse shoulder arthroplasty using Humelock II reversible prosthesis in elderly patients.