We reviewed the CT findings of 13 patients with histologically proved alveolar echinococcosis of the liver. Seven of these patients had hilar involvement, which caused dilatation of intrahepatic bile ducts and invasion of the portal vein or portal branches. In two of these patients we found marked atrophy of the right lobe and in one patient marked atrophy of the left lobe in addition to various CT findings previously reported for alveolar echinococcosis of the liver. The occurrence of lobar atrophy of the liver caused by alveolar echinococcosis has not been previously reported. We concluded that, when a mass lesion with hilar infiltration causing lobar atrophy is found in endemic areas, alveolar echinococcosis should be considered in the differential diagnosis in addition to malignant neoplasms.