Gelatin sponge moistened with lipiodol was prepared for use in portal embolization to improve percutaneous transhepatic portal embolization as preoperative management of patients undergoing extensive liver resection. For one sheet of gelatin sponge (20 x 60 x 7mm)0.5ml of lipiodol was used. Five sheets cut to 2mm square pieces and mixed with physiological saline solution were injected into the right portal vein. This embolic material proved safer and more reliable than gelatin sponge mixed with water-soluble contrast medium, because it provided sufficient opacification to grasp the extent of embolization and prevented back flow.