The surgical placement of hepatic arterial cannulas, followed by intra-arterial chemotherapy, is a promising technique for the treatment of unresectable hepatic malignancies. Complete perfusion of the liver with drugs is essential, but may be difficult to achieve in some patients with variant arterial anatomy. In 79 patients, we encountered 15 with variant anatomy that precluded standard single or dual cannulation techniques. In 12 patients variant lobar arteries were ligated at surgery. Postoperative transarterial coil occlusion was used in three patients. In each case, the remaining hepatic lobar artery was perfused with a single catheter. Complete bilobar hepatic perfusion was documented by a technetium 99m macroaggregated albumin scan in 13 of 15 (87%) patients. Of patients scanned more than 5 days after occlusion, six of six (100%) had full perfusion of the region supplied by the variant lobar vessels. Postocclusion hepatic arteriography demonstrated translobar collateral vessels that provided perfusion of the region of the occluded variant artery. There was no added morbidity from lobar arterial occlusion and no disparity in tumor response between perfusion by direct cannulation and perfusion by collateral flow. Occlusion of variant hepatic lobar arteries in conjunction with single catheter cannulation to infuse the remaining lobar vessels is a useful technique to provide total hepatic arterial perfusion in patients with variant hepatic arterial anatomy.