The safety of naproxen suspension was assessed in an open study in children with juvenile rheumatoid arthritis. Fifty-eight patients aged 1 to 13 (mean, 4.5 years) were studied. Based on the patient's condition, naproxen was prescribed at dosages ranging from 9 to 20 mg/kg/day. Follow-up assessments were made during regular clinic visits, as often as deemed necessary by the physician. Forty-four patients completed a minimum of six months' treatment. One patient was lost to follow up and 13 were withdrawn early: three because of unsatisfactory therapeutic response, one because of disease remission, five because of taste complaints, and four because of other side effects. The side effects were mostly gastrointestinal and were mild to moderate in severity. Investigators' subjective evaluations indicated that 84% of the patients who completed six months' treatment had good or excellent therapeutic responses at termination. The study results demonstrated that naproxen suspension is a well-tolerated anti-inflammatory agent for young children with juvenile rheumatoid arthritis.