Forty-six patients with rheumatoid arthritis underwent metacarpophalangeal-joint arthroplasty of the index through little fingers on 210 joints in fifty-five hands using the Swanson-design silicone-rubber spacer. The patients were followed for two to eight years (average, five and one-quarter years). They were evaluated both preoperatively and postoperatively for range of motion, deformity, subjective sense, grip strength, and prehension. In the initial postoperative evaluation, the majority of patients expressed a strong subjective impression of improvement. Ulnar drift improved from the preoperative average of 25 degrees to less than 5 degrees. The preoperative average extension deficit decreased from 56 to 10 degrees, while the average range of motion increased from 17 to 51 degrees. In the long-term postoperative evaluation, the average ulnar drift had increased to 12 degrees, the average extension deficit had increased to 22 degrees, and the average range of motion had decreased to 39 degrees. Grip strength and prehension did not significantly improve at either evaluation. There were no fractures of the prosthesis and no patient had synovitis. We have found the procedure to be useful for the correction of deformity, increasing range of motion of the fingers, and improving the patient's sense of well-being.