The Pediatric Rheumatology Collaborative Study Group was established in 1973 to undertake systematic trials of new drugs in the treatment of juvenile rheumatoid arthritis. The first drug evaluated was tolmetin (1-methyl-5-p-toluoylpyrrole-2 acetic acid), a new nonsteroid anti-inflammatory agent. A four-week open trial with 30 patients and a subsequent 12-week double-blind trial against aspirin with 107 patients were conducted. Tolmetin and aspirin had equal anti-inflammatory and analgesic effects in the treatment of JRA. Elevations of transaminase values attributed to aspirin were not found with tolmetin. Adverse effects accompanying administration of tolmetin did not appear to be of major clinical significance.