Computed tomography revealed dilatation of the intrahepatic bile ducts in 25 out of 135 cases of hepatocellular carcinoma. In 6 (4.5%) of these 25 cases the dilatation was generalised, while in the remaining 19 cases (14%) dilatation was localised. In each group 3 cases of intraductal tumour growth was confirmed either at operation or autopsy. With metastatic liver tumour, generalised dilatation was observed in 6 cases (7%) and localised dilatation in 3 (3.5%) out of 85 cases. Localised dilatation was found with higher incidence in hepatocellular carcinoma than in metastatic tumour. This may indicate that the incidence of intraductal infiltration is high in cases of hepatocellular carcinoma. When a relatively small tumour is associated with dilatation of bile ducts, it is more probable that the tumour is a hepatocellular carcinoma than a hepatic metastasis.