Three patients with chronic urticaria, two of whom also had angioedema, were treated with oral cyclosporine, 6 mg/kg per day. In each patient, complete resolution of symptoms occurred within the first week of therapy; however, all patients eventually had to stop therapy as a result of side effects. On stopping therapy, all side effects resolved and the urticaria and angioedema recurred. Although cyclosporine therapy is not an appropriate treatment of urticaria, the results of this preliminary study suggest that cyclosporine and related drugs should be investigated in the treatment of mast cell-mediated diseases.