To compare the efficacy of regional and systemic infusions of hepatic tumors, and to correlate this with tumor perfusion, 29 New Zealand white rabbits underwent perfusion of VX-2 hepatic implants. Tritium-labeled fluorodeoxyuridine (H3-FUDR) and technetium-99m-labeled macroaggregated albumin (Tc 99m-MAA) were infused through the hepatic artery, portal vein, and peripheral vein. Hepatic artery infusion resulted in a significantly improved tumor-to-liver ratio of FUDR uptake (p less than 0.001). The increased tumor uptake correlated with a two-fold increase in tumor arterial blood flow as compared with normal liver demonstrated by the MAA infusion. We conclude that infusional therapy is superior to both portal vein and systemic infusions. Portal vein infusion results in no uptake of drug by the tumor. Hepatic artery scintigraphy with MAA may be useful in selecting appropriate patients for this type of therapy.