One hundred eighty-nine patients with rheumatoid arthritis were entered into a prospective, controlled, double-blind multicenter trial comparing placebo and methotrexate (MTX). One hundred ten patients completed 18 weeks of therapy. No remissions were seen, but patients able to tolerate low-dose pulse MTX therapy were significantly improved, compared with patients receiving placebo therapy, for all clinical variables measured, including joint pain/tenderness and swelling counts, rheumatoid nodules, and patient and physician assessment of disease activity. MTX treatment demonstrated statistically significant improvement over placebo in patients with anemia, elevated erythrocyte sedimentation rate, and rheumatoid factor. However, nearly one-third of the patients receiving MTX were withdrawn for adverse drug reactions, of which elevated levels of liver enzymes was the most common. Pancytopenia occurred in 2 patients taking MTX. All adverse drug effects resolved without sequelae. MTX appears to be effective in the treatment of active rheumatoid arthritis but requires close monitoring for toxicity.