Eighty-two liver specimens were studied by both computed tomography (CT) and pathological examination with serial sectioning. In vitro studies showed low density structures within 57 normal livers to be due to portal and hepatic vessels but not to bile duets. A liver with a minimum of 70 fatty infiltration could he diagnosed correctly on CD. Concerning the presence or absence of circumscribed liver disease, sensitivity was 80 and was with respect to the total number of space occupying liver lesions (364 in 18 specimens) sensitivity was 72% The smallest metastases detect able on CI were 0.5 cm in diameter, but CT disclosed focal lesions of this small size in only 75% of the cases. In contrast to previously reported In vivo CT studies, metastases were often found to be of higher density than normal liver tissue In vitro.