The results of Swanson and Avanta metacarpophalangeal joint arthroplasties in rheumatoid patients were compared in a prospective, randomized study of 30 patients (120 implants). At 2-year follow-up, grip strength was measured, hand function was assessed with the Sollerman test and the subjective outcome was determined with visual analogue scores. With both implants ulnar deviation and flexion deformities decreased, and there was no difference between the groups. The increase in range of motion was 7 degrees greater with Avanta implants than with Swanson implants. Grip strength and hand function were unaltered but the visual analogue scales showed decreased pain levels and subjective improvements in hand function, grip strength and cosmesis. Twenty-four of 30 patients were satisfied. Fracture of the silicone spacer occurred with 12 Avanta (20%) and eight Swanson implants (13%), with a higher fracture frequency in men.