The diagnosis and definition of hepatic malignancies by use of arterial enhanced computerized tomographic scanning. Axial computerized tomography is a useful tool in the evaluation of either primary or metastatic hepatic neoplasms. An adjunct to this technique is visceral arterial enhanced computerized tomography (AECT). To determine the effectiveness of this modality, bolus intravenous enhanced computerized tomography scans and AECT were compared and correlated to operative findings. Fifty-four consecutive patients were evaluated by AECT and bolus intravenous enhanced computerized tomography over a 30-month period (May 1986 to August 1989) for suspected primary or metastatic hepatic malignancies. Forty-four patients (81%) had hepatic lesions. Fifty-two percent (23 of 44 patients) of the metastatic tumors were from colonic or rectal primary lesions, and 20% were hepatocellular primary lesions. The remainder of the lesions were metastases from a variety of primary lesions. When studies were compared, 34% of the patients (15 of 44 patients) differed in either the location or total number of lesions noted. The lesions of three of the 15 patients (20%) were determined unresectable on the basis of AECT. Of the remaining patients, planned resections were revised in seven patients to either lesser or greater procedures. The number of lesions found at laparotomy equaled the number found by AECT in all but two cases. AECT caused no complications. AECT improved our ability to identify and localize primary and metastatic lesions of the liver. This technique offers the advantage of preoperative definition of the hepatic arterial and portal venous anatomy. 