121 patients with active rheumatoid arthritis, 91 of whom had proved intolerant of other nonsteroidal anti-inflammatory agents, were treated for a mean of 10 months with naproxen. A dosage of 250 mg twice daily produced sustained improvement in most of the standard clinical measurements. 28 patients complained of side effects, with a lower than expected incidence of gastrointestinal complaints and no drug-induced rash being recorded. 19 patients withdrew from the trial because of side effects, while a further 22 withdrew because the drug was ineffective. Naproxen is a useful drug for long-term use in patients with rheumatoid arthritis, including those who have proved intolerant of or experienced inadequate symptomatic relief from other nonsteriodal anti-inflammatory agents.