Methrazone, a non-steroidal anti-inflammatory drug, was used on a monitored release study in general practice to treat 2,693 patients with rheumatoid or osteoarthritis. In a dose of 200 mg three times daily, it appeared to produce clear benefit in between 50% and 60% of patients. Adverse reactions such as dyspepsia and skin rash led to the drug being withdrawn in 11% of patients. There were three major adverse reactions possibly due to the drug (haematemesis, rectal bleeding and acute purpura), but no cases of severe leucopenia or thrombocytopenia. Methrazone is a useful anti-inflammatory agent. In particular, it is unlikely to cause interactions with other drugs, including cardiac glycosides such as digoxin.