A double-blind multicenter cross-over study was conducted on 166 outpatients with painful chronic osteoarthritis of the hip and of the femoro-tibial joints, to compare the effectiveness of glafenine and paracetamol. Patients were randomly assigned to receive over a period of a week, either 400 mg of glafenine or 1000 mg of paracetamol twice a day at 8 a.m. and 4 p.m. in order to fill up the physical activity period during the daytime. This interval between tablet intake was chosen according to the design of the model. At the end of the week treatment period, patients crossed over. There was no wash out period between treatments. The following measurements: pain intensity (on Huskisson's visual analogue scale), functional index for hip and knee diseases, patients' overall opinion, patient preference, were evaluated at days 0, 7, 14. The results showed that both treatments produced effective analgesia but the improvement was significantly greater and observed in a larger number of cases when using glafenine rather than paracetamol. Fifty-one per cent of the nonresponsive patients to paracetamol could benefit from the glafenine treatment and 18 per cent of patients suffering from hip or knee osteoarthritis in this study showed improvement only with glafenine. Safety and biological tolerance were satisfactory with both drugs.