A double-blind study was carried out to compare the effects of ketoprofen and phenylbutazone in acute gouty arthritis. Two groups of patients, each consisting of 23 males, received intramuscular injections of either phenylbutazone (2 X 300 mg daily) or ketoprofen (2 X 50 mg daily) for a period of 7 days. The drug effects were assessed both subjectively and objectively. There was an excellent therapeutic effect in both groups. In general, no statistically-significant differences were detected between the two preparations. However, ketoprofen appears to be slightly better tolerated with respect to the incidence of systemic and local side effects. Thus, the administration of ketoprofen can be recommended in cases of acute gouty arthritis.