STUDIES IN THIS and other laboratories indicate that both primary and secondary hepatic tumors receive essentially all of their blood supply from the hepatic artery.1,2 Accordingly, the dual circulation of the liver presents a unique opportunity to study the effect of intra-arterial infusion of a chemotherapeutic agent while counter-acting the local and systemic effects of the drug by the simultaneous infusion of an antagonist into the portal venous circulation. Since the 5-year survival rate of patients with hepatic metastases or carcinoma of the gallbladder is 0% to 2%, it seems worthwhile to evaluate the safety and efficacy of this method of therapy with currently available drugs. Methods and Materials Healthy, adult, mixed-breed dogs, weighing 20 to 30 kg (44 to 66 1b), were used for this experiment. The animals were anesthetized with sodium pentobarbital and opened through an upper abdominal midline incision. Following liver biopsy, a No. 90 polyethylene