We carried out percutaneous transhepatic portography (PTP) in 182 patients with liver, biliary tract, or pancreatic disease. With anterior and lateral views of selective portograms and stereoscopic x-rays, we investigated the ramifications of the intrahepatic portal vein. There were 3 patterns of branching of the portal trunk and of the left branch of the portal vein. There were 8 such patterns for the right anterior branch, with either 4 or 5 major branches arising from it. Branching of the right posterior branch was classified into 4 patterns; simple branching into 2 (one, the posterior superior branch, the other, the posterior inferior branch) was found in only 97 of the 164 cases inspected. These results suggested that the liver cannot necessarily be divided into 8 segments. Branching of the intrahepatic portal vein is very complex; therefore, the pattern of ramifications of the portal vein must be ascertained anew for every patient for whom systematic segmentectomy is contemplated.