For improved visualization of the intrahepatic portal vein, balloon-occluded superior mesenteric arteriography was performed using a torque-controlled balloon catheter after injection of 20 micrograms prostaglandin E1. In patients who underwent arterial portography twice, i.e., by the method using prostaglandin E1 alone and the prostaglandin E1 plus the balloon method, the latter method provided better visualization, particularly in cases in which an aberrant right hepatic artery arose from the superior mesenteric artery.