Hand function, determined by a standardized test, was compared before and after total metacarpophalangeal joint replacement with the Swanson Silastic rubber metacarpophalangeal prosthesis in patients with destructive rheumatoid arthritis. Two groups of rheumatoid patients were tested. Group 1 consisted of 10 patients who were examined 3 to 4 months after surgery. Group 2 included 11 patients who were evaluated 6 to 12 months postoperatively. Each group represented 43 prosthetic replacement procedures performed on 12 hands. Results indicate substantial postoperative improvement in tip prehension and grasp, while performance remained essentially unchanged for lateral prehension, pinch force, and power grip. A postoperative program of therapeutic exercises, functional hand activities and splinting is discussed.