We report here on the imaging findings of a case of autoimmune cholangitis that involved a segmental bile duct of the liver. Abdominal computed tomogram showed ill-defined low-attenuation lesion at the hilar portion of the right hepatic lobe, and this was associated with peripheral intrahepatic bile duct dilatation. Gadolinium enhanced liver magnetic resonance imaging (MRI) showed wall thickening with periductal enhancement along the segmental tributaries of the right intrahepatic bile duct. The pathologic findings revealed lymphoplasmacytic infiltration and severe fibrosis, indicating autoimmune cholangitis.