Azathioprine. An effective, corticosteroid-sparing therapy for patients with recalcitrant cutaneous lupus erythematosus or with recalcitrant cutaneous leukocytoclastic vasculitis. Azathioprine sodium has been reported to be effective therapy for chronic cutaneous lupus erythematosus (LE) but rarely for chronic cutaneous leukocytoclastic vasculitis (LV). We used azathioprine in the treatment of six patients with cutaneous LE, four of whom had subacute cutaneous (nonscarring) LE and two of whom had chronic cutaneous (scarring, discoid) LE, and six patients with chronic cutaneous LV. The conditions of all patients had been resistant to conventional therapy, and they required long-term oral corticosteroid therapy for control of their disease. Two of the patients with LE had prominent palmar and/or plantar involvement. Three patients with LE had an excellent response to azathioprine, with near complete clearing of the skin lesions, allowing a decrease in prednisone dosage. One patient with LE initially demonstrated significant improvement, but azathioprine therapy had to be discontinued because of pancreatitis. The treatment failed in two patients with LE; one had nausea and the other repeatedly developed a drug-induced fever. Five of the six patients with LV had improved conditions, with complete control of the disease occurring in two patients and partial control in three patients. Azathioprine is effective for some patients with cutaneous LE and chronic cutaneous LV, but it should be reserved for patients with severe disease in whom more conventional treatment fails. 