A double-blind, crossover study was carried out in 30 patients with active, classical or definite rheumatoid arthritis to compare the effect of 200 mg flurbiprofen per day with that of 100 mg indomethacin per day. Patients received, at random, each drug for a period of 2 weeks separated by a weeks' wash-out period on placebo. Assessments were made before the start of the trial and at weekly intervals of pain, morning stiffness, grip strength, articular index, walking time, and finger joint size. Patients' preference for any particular treatment period was recorded at the end of the trial. Laboratory investigations were carried out before and during the trial. Both drugs shows statistically significant improvement over baseline assessments, although there was little difference between the two active treatment periods. More patients preferred the treatment period with flurbiprofen, and this was probably related to the fewer side-effects which were reported with this drug.