Gross deformity of the liver associated with hilar carcinoma is rare. In 17 patients with hilar cholangiocarcinoma and intrahepatic bile duct dilatation, the relationships between lobar or segmental atrophy, compensatory hypertrophy, and patency of portal vein branches were evaluated with computed tomography (CT) and angiography. All six patients with obstructed or narrowed portal veins (group A) had lobar or segmental atrophy on CT scans and angiograms. Compensatory hypertrophy was observed in the unaffected lobe with a patent portal vein in five. In contrast, neither hepatic atrophy nor hypertrophy was demonstrated in the other 11 patients with patent portal veins. All group A patients had differences in hepatic attenuation on CT scans or dense opacification during the hepatogram phase of angiography. Biliary decompression was optimized when the bile duct selected for percutaneous drainage paralleled a patent portal vein. Knowledge of radiologic findings will assist in determining the primary site along the bile duct from which carcinoma has arisen.