A 6-week double-blind, parallel controlled, randomized study was carried out to compare the efficacy and tolerability of 100 mg flurbiprofen twice daily with 375 mg naproxen twice daily in patients with rheumatoid arthritis. One hundred and six patients from five centres were evaluable; 52 from the flurbiprofen group and 54 from the naproxen group. Evaluation of the primary efficacy parameters demonstrated no difference in efficacy between the treatment groups. In general, the results of evaluation of the secondary efficacy parameters also supported similar improvement for both treatment groups. The overall incidence of adverse clinical/laboratory experiences was similar between the treatment groups. Five patients, 3 flurbiprofen and 2 naproxen-treated, discontinued the study, all because of gastro-intestinal intolerance.