Naproxen (NAP) (10 mg/kg/day) and acetylsalicylic acid (ASA) (75 mg/kg/day) were compared in a 24-week randomized block, controlled, parallel, double-blind study in 80 patients with pauciarticular or polyarticular juvenile rheumatoid arthritis. Five NAP-treated compared with 20 ASA-treated patients stopped therapy because of adverse reactions. Both drug regimens seemed to be therapeutically effective. The outcome of the study indicated that ASA may have a slight advantage over NAP with regard to efficacy. However, the changes in disease activity measurements were similar in the two treatment groups.