SUMMARY.— Eighteen patients with intractable or severe psoriasis have been treated for up to 28 months with intermittent large oral doses of methotrexate. The disease was completely controlled in 9 and partially controlled in 5 patients. Severe clinical side-effects were seen in 5 patients, in 4 of whom therapy had to he abandoned. These effects were severe abdominal pain and vomiting in 2; reactivation of colitis, serious ataxia, and epidermal necrolysis in 1 patient each. Concurrent administration of aspirin probably contributed to toxicity by potentiating the action of methotrexate in 2 of these cases.

No serious haematological or biochemical abnormalities developed but mild transient leucopenia occurred in 2, thrombocytopenia in 1, and raised serum transaminases in 7.