Osteoarthritis and rheumatoid arthritis are very common conditions in our aging population. Patients with this condition usually complain of pain and decreased range of motion that affect their activities of daily living. This study is a retrospective review of a third-generation shoulder arthroplasty performed for nontraumatic conditions such as osteoarthritis and rheumatoid arthritis. All surgeries were performed by the same surgeon, between 1997 and 2000, with an average postoperative follow-up of 28 months. Thirty-six patients, with 28 total shoulder arthroplasties and nine hemiarthroplasties were included in this study. The distribution of shoulder pathology was as follows: 25 patients with osteoarthritis and 11 patients with rheumatoid arthritis. A preoperative and postoperative evaluation was available for every patient, including a visual analog scale, a questionnaire of activities of daily living, active range of motion, and strength. The American Shoulder and Elbow Surgeons shoulder index and the University of California, Los Angeles rating scale were calculated for all patients. There was an average increase of 46 degrees in forward flexion, 23 degrees in external rotation, 40 points in the American Shoulder and Elbow Surgeons shoulder index, and 17 points in the University of California, Los Angeles scale. The results of this study demonstrate that excellent pain relief, increase in range of motion, as well as improvement in the activities of daily living performance can be obtained with this thirdgeneration shoulder prosthesis.