The UCLA total shoulder arthroplasty was designed to mobilize the shoulder joint in order to permit normal anthropometric range of motion and durable long-term fixation of the components. The prosthesis is fundamentally nonconstrained for the usual arthritic conditions, currently with four sizes of femoral and glenoid components. For patients with deficient and irreparable rotator cuffs, additional restraint may be effected by using a superior glenoid subacromial rim. The first 11 patients have been followed for 1 1/2 to 3 1/2-years; relief of pain has been complete in all but two patients. The function and range of motion results were related to the status of the rotator cuff; five patients achieved excellent results, including two with osteoarthritis who had near normal function. Patients with deficient rotator cuffs achieved functional use of the extremity but without full range of motion. Functionally, in addition to the five patients who were rated excellent, two were rated as being good, three fair, and one poor. In addition to five with excellent range of motion, there were three good and four fair ratings. Two patients, one with grossly deficient musculature caused by a gunshot wound and a second who was posttrauma required revision surgery with a subacromial glenoid prosthesis. This prosthesis is now frequently utilized if muscles and rotator cuff are deficient at the primary surgery, in order to provide additional restraint. Determination of the efficacy of hooded components will require further follow-up. The additional size ranges and components together with improved instrumentation have greatly facilitated recent surgery.