Liver function and clotting tests were evaluated in 39 patients with variceal bleeding prior to superior mesenteric artery vasopressin infusion. In six patients with mild hepatic dysfunction (Child's class A), permanent control of hemorrhage was achieved in all six and all survived the hospitalization. In 21 patients with moderate dysfunction (Child's class B), permanent control of hemorrhage was achieved in 13 (62%) and temporary control for 24 hr or longer in the remaining eight (38%). Survival in class B was 67% (14 of 21). In only four of 12 patients with severe hepatic dysfunction (Child's class C) was control of hemorrhage achieved (33 percent). None of these patients survived. Therapeutic failure also was associated with clotting derangements and the initial bleeding rate. It is concluded that the effectiveness of vasopressin in variceal hemorrhage is a function of the underlying liver disease and derangements in clotting function.