We herein report a case of monolobar hepatobiliary fibropolycystic disease. A 75-year-old woman presented with heartburn. Imaging modalities including US, CT, and MRI revealed marked atrophy and multiple biliary cysts of the hepatic left lobe. The hepatic right lobe was normal. ERCP and bile duct endoscopy revealed anomalous pancreaticobiliary union, choledochal dilation, dilation of left intrahepatic bile ducts, and small choledochal non-invasive adenocarcinoma. Polycystic kidney diseases were absent. The patient underwent pancreatico-duodenectomy and extended hepatic left lobectomy. Grossly, the hepatic left lobe was markedly atrophic, and studded with numerous biliary cysts. The left intrahepatic bile ducts were dilated (Caroli's disease) and the common bile duct showed type I choledochal dilation. The right hepatic lobe was normal. Histologically, the hepatic left lobe was replaced by fibroelastosis. The intrahepatic bile ducts showed ductal plate malformation such as irregular contours, invaginations, and protrusions. The numerous biliary cysts also showed ductal plate malformation. There were numerous persistent ductal plates and microhamartomas. Many hyalinized destructive biliary cysts and ductal plates were recognized. The liver parenchyma was scant and free of hepatocellular malformations. The portal veins showed old obliterative portal thrombosis. The right hepatic lobe was normal. Immunohistochemically, the biliary cells were positive for cytokeratin 7, 8, 18 and 19, and MUC6 and CD10, but negative for MUC2 and MUC5AC. The biliary cysts, persistent ductal plate, and microhamartomas were positive for fetal apomucin antigen MUC1.