A 19 month old male infant with a mesenchymal hamartoma of the liver underwent an extended right hepatectomy. Serum bilirubin gradually rose until 3 months after the surgery, and obstructive jaundice and acholic stools were manifested at 6 months. Percutaneous transhepatic cholangio-drainage was performed. Cholangiography showed dilation of the intrahepatic bile duct of the residual lateral segment and complete obstruction of the extrahepatic bile duct. A second operation for reconstruction of the biliary tract was performed 10 months after the first surgery. No aspect of an extrahepatic biliary tract was found. Histological inspection of a surgical specimen of remnant tissue revealed only cicatricial connective tissue without any biliary structures. The clinical course has been uneventful for 18 months since the second surgery. The cause of bile duct atresia in this case is strongly suggested to be an ischemic change due to devascularization of the extrahepatic biliary tract following hepatic resection because of a tumor. To prevent this kind of complication, hepatico-enterostomy should be performed close to the cut surface of the liver.