Fifteen patients with rheumatoid arthritis had 19 elbow arthroplasties with the Wadsworth type of surface replacement prosthesis. After a follow-up period averaging 30 months, 11 patients with 15 elbow arthroplasties were entirely satisfied with their freedom from pain and range of movement. Radiologically, however, the humeral component was loose in 10 of the 19 elbows and the ulnar component in 5. Two patients had reoperation, one to remove a prosthesis for early deep infection and one to exchange a humeral component which was loose. The risk of mechanical loosening is reduced by accurate positioning of the humeral component, but there is a high potential for failure. Changes in the design of the prosthesis and better instrumentation for alignment of the components are desirable. Prosthetic replacement of the elbow should still be regarded as experimental.