The response of psoriatic arthritis to methotrexate was evaluated retrospectively in 59 consecutive patients. Initially almost all received 15 mg weekly. When clinical improvement occurred, the dose was gradually reduced. In 7 patients methotrexate had to be discontinued within a year due to adverse reactions. The remaining 52 patients were treated from 1 to 11 years, median 3 years. Among these a modest improvement was seen in 21, while in 22 the signs of inflammatory joint disease almost disappeared. The favourable response was related to the short duration of arthritis, but unrelated to the severity of the disease.