PURPOSE: To describe the radiologic features of computed tomography(CT) in hepatocelluar carcinoma(HCC) with bile duct involvement. MATERIALS AND METHODS: We retrospectively analyzed the two phase spiral CT findings of 31 patients in whom HCC with bile duct invasion (n=28) or compression (n=3), was diagnosed. Eight of these underwent follow-up CT after transarterial chemoembolization. We analyzed the size, type, location, enhancement pattern, and lipiodol retention of parenchymal and intraductal masses, as well as their and lymphadenopathy. RESULTS: In all patients with bile duct invasion, single or multiple masses were demonstrated in the bile ducts. Intraductal masses showed the same enhancement characteristics as the parenchymal mass (kappa 0.550, p < .001), and were contiguous to this mass. In 14 of 28 patients, intraductal masses filled the peripheral intrahepatic bile ducts and extended to the common bile ducts. In the other 14, the parenchymal mass extended to the area of the porta hepatis and then directly invaded the large ducts. In nine of the 28 patients, there was a hypoattenuated cleft between the intraductal mass and ductal wall. In six, a parenchymal mass was not apparent (n = 2), or was smaller than 2cm (n = 4). In five of eight patients (62.5%), follow-up CT after transarterial chemoembolization showed compact or partial lipiodol retention within the intraductal mass. In patients with bile duct compression, perihilar lymph nodes were noted along with the dilated intrahepatic duct but no intraductal mass was demonstrated in the duct. CONCLUSION: Hepatocellular carcinomas cause bile duct dilatation either by direct invasion or by extrinsic compression of the bile duct with surrounding enlarged nodes. For the diagnosis of this condition, CT is helpful.