PURPOSE: To evaluate the enhancement patterns of nodular and massive hepatocellular carcinoma (HCC), with or without portal vein thrombosis, on three-phase spiral CT. MATERIALS AND METHODS: Contrast enhancement patterns in 61 patients with HCC were retrospectively analysed. Three-phase spiral CT images of the hepatic arterial dominant phase, portal dominant phase, and delayed phase were obtained 30, 60-70, and 360 seconds after the injection of contrast material was initiated. Tumors were divided into grossly nodular and massive type and enhancement patterns of HCC, with and without portal vein thrombosis, were compared. These patterns were divided into three groups, as follows: High/High/Low; High/Low/Low; Low/Low/Low. HCC with portal vein thrombosis was found in 21 of 61 cases ; this carcinoma without portal vein thrombosis was found in 40 cases. The nodular type accounted for 39 cases, and the massive type for 22. RESULTS: In 21 cases of HCC with portal vein thrombosis, the most common enhancement pattern was L/L/L, and was seen in 13 cases (62%); H/L/L was seen in eight (38%), but H/H/L was not seen. In 40 cases of HCC without portal vein thrombosis, the most common enhancement pattern was H/L/L, seen in 25 cases (63%) ; this was followed by L/L/L (11 cases ; 27%), and H/H/L (4 cases ; 10%). In the arterial dominant phase, among cases of HCC with portal vein thrombosis, low attenuation was more common (13/21) than high (8/21);among cases of HCC without portal vein thrombosis, high attenuation was more common (29/40) than low (11/40). Among 39 nodular-type cases, HCC with portal vein thrombosis was found in six (H/H/L and L/L/L: three each), and HCCwithout portal vein thrombosis was seen in 33 (H/L/L: 22; L/L/L: 7; H/H/L; 4). Among 22 cases of the massive type, HCC with portal vein thrombosis accounted for 15 (L/L/L: 10, H/L/L: 5), and seven cases without portal vein thrombosis were seen (L/L/L: 4 ; H/L/L : 3). CONCLUSION: On Three-phase spiral CT, HCC showed different enhancing patterns according tumor type and the presence of portal vein thrombosis.