The study was aimed at comparing effectiveness, safety and possible steroid sparing effects of indoprofen (800 mg/day) and indomethacin (100 mg/day), in patients with classical or definite rheumatoid arthritis, in active phase, receiving basic steroid treatment at a fixed, not reducible dosage. Treatments were given in double-blind condition, for 1,3 or 6 months, and 97 patients were evaluated. A significant improvement of baseline conditions was obtained with both drugs in all variables considered for evaluation of effectiveness. The initial steroid dosage could be reduced 72% in the indoprofen group and 53% in the indomethacin group; 50% of the patients receiving indoprofen and 22.4% of those receiving indomethacin stopped steroid intake during the trial. Adverse reactions, considered drug related, were observed in 6.7% of patients in the indoprofen group and 34.1% of those given indomethacin.