Nineteen consecutive patients with malignant hilar obstruction were imaged with angiography, CT portography, and ultrasonography with color and spectral Doppler technique; all had surgical pathologic correlation. At surgery, 12 of 19 patients (63%) were found to have portal vein involvement; 15 of 19 (79%) had parenchymal invasion; and 11 of 19 (58%) had lobar atrophy. Level of biliary obstruction was determined in seven of 19 patients (37%) without drainage catheters. No difference was found between ultrasonography and angiography with CT portography for diagnosis of atrophy, level of bile duct obstruction, hepatic involvement, or venous invasion. Extrahepatic metastases in nine of 19 patients (47%) were poorly predicted by both CT portography and ultrasonography.