Congenital absence of the portal vein (CAPV) is a rare malformation that is often accompanied by other anomalies such as cardiac and skeletal malformations and/or hepatic tumors. We describe here a case of CAPV complicating hepatic tumors in a 16-year-old Japanese girl. Abdominal ultrasonography revealed a hyperechoic tumor in the liver and dilatation of the portal vein that appeared to be connected directly with the inferior vena cava. Subsequent abdominal computed tomography (CT) revealed tumors and magnetic resonance angiography confirmed that the portal vein entered directly into the inferior vena cava just above the liver. In addition, there was absence of the right portal vein and the left intrahepatic branch except for the presence of left portal vein only within the porta hepatis. These findings led to a diagnosis of CAPV complicated hepatic tumors. Careful monitoring of these hepatic tumors is ongoing due to the possibility of malignant transformation.