Twenty-four patients with active rheumatoid arthritis were studied in a 4-week double-blind, placebo-controlled, parallel group trial. They were treated with a low dose (25, 50, and 100 mg twice daily) or high dose (100, 200, or 300 mg twice daily) of etodolac or with placebo. In both groups four patients received placebo and eight the active drug in a fixed-titration regimen. Doses were increased weekly and kept at the highest level during the last 2 weeks. Clinical and laboratory assessments were completed before drug and on days 8, 15, and 29. Seventeen patients completed 29 days and seven discontinued the study earlier: six on placebo and one on low dose. Etodolac-low dose was significantly more effective than placebo in nine of ten clinical assessments and in all ten at high dose. Etodolac was well tolerated. All patients had negative tests for occult blood at all times. Etodolac was an effective anti-inflammatory agent and appeared to be safe in doses of 50-600 mg per day.