Timegadine, a new antiinflammatory agent, is found to be a potent, competitive inhibitor of prostaglandin synthetase which also inhibits cyclo-oxygenase (COX) and lipoxygenase. Daily oral doses of 10 to 30 mg/kg of Timegadine significantly inhibit both the primary and secondary lesions of adjuvant arthritis when the treatment is initiated on the day of the disease induction and continues for 28 days. Timegadine is able specifically to prevent the development of the swelling of the non-injected paw until 28 days after the adjuvant injection when administered for 5 days prior to and 5 days after the induction of the disease, in analogy with the effect of cyclophosphamide[1].