Studies of intrahepatic arteries in vivo and after death give dramatically different results concerning the human hepatic circulation. Corrosion casts of human liver vasculature support the existing belief that hepatic arteries are end-arteries. However, in vivo studies using angiographic techniques after ligation of either the left or the right ramus of the hepatic artery demonstrate intrahepatic translobar collateral arteries capable of perfusing the entire occluded arterial system. There is no intermediate filling of sinusoids nor of portal venules. Traditional statements that hepatic arteries are end-arteries cannot be supported by the present findings.