The effects of cyclosporine were studied in nine patients suffering from pemphigus vulgaris. Of four patients treated with cyclosporine alone, only one cleared. Of four corticosteroid-resistant pemphigus vulgaris patients, all improved after cyclosporine addition to corticosteroids. The last patient treated from the beginning with a combined treatment (cyclosporine-corticosteroids) did not respond. The main advantage of using cyclosporine is to allow a decrease in corticosteroid dosages and to permit treating corticosteroid-resistant pemphigus vulgaris patients. No detectable irreversible side effects were noted. The treatment was discontinued in two patients because of reversible side effects. Cyclosporine alone does not seem to be an adequate treatment of the acute phase of pemphigus vulgaris but could be used in addition to corticosteroids. The most important drawback of cyclosporine treatment is the occurrence of clinically silent renal dysfunction (tubular involvement and interstitial fibrosis), which may occur during long-term treatments. More studies need to be carried out to determine the effects of low doses of cyclosporine on renal function in patients who have normal renal functions.