Forty patients with psoriasis treated with methotrexatc (MTX) are reviewed. MTX was particularly effective in controlling; erythrodermic and generalized pustular psoriasis. The treatment was discontinued in seven patients due to nausea in two and because of abnormal laboratory tests in five. Two patients developed toxic epidermal necrolysis (TEN) and died. Patients under 60 years of age had a liver biopsy before treatment and repeat biopsy after each cumulative MTX dose of 1500 mg. We consider that MTX is the drug of choice for treating difficult psoriasis.