One hundred and twenty-three patients with rheumatoid arthritis (RA) who successfully completed a randomized trial comparing oral methotrexate (MTX) to auranofin enrolled in a longterm prospective study of oral MTX. Of the 91 patients who completed 24 months of therapy, a significant (p = 0.0001) improvement was noted compared to baseline in all clinical disease variables and the Westergren erythrocyte sedimentation rate (ESR). Marked improvement occurred in 94 (76%) and 98 (80%) of the patients in the joint pain/tenderness index and joint swelling index at the last evaluable visit (mean 26 months). Of the 77 patients with an elevated ESR at baseline, 29 (38%) patients normalized it (less than 20 mm/h) while receiving therapy (p less than 0.01). A significant reduction in prednisone dose was also seen. Adverse events occurred frequently but were generally mild in severity. Twenty-seven patients (22%) withdrew during the study. Four (3%) withdrew due to lack of efficacy, and 6 (5%) because of adverse experiences. The overall probability of continuing therapy in the study for 48 months was projected at 72%. This large prospective study supports the observation of earlier smaller studies that MTX is an effective drug in the treatment of RA.