Segmental anatomy has been investigated on 54 pig livers by bench-top radiology and ultrasonography of hepatic and portal vessels and bile ducts and dissection of suprahepatic veins. Eight segments were recognized, homologous to those of the human liver. Major variations were found only of arterial distribution. The inferior vena cava invariably ran within the parenchyma of the right lobe and close to the liver hilum; suprahepatic veins were also entirely intraparenchymal. Therefore, the pig liver can easily be divided into two halves, but only the right one can be used for reduced-size grafting into a recipient.