PURPOSE: To compare the contrast enhancement patterns of hepatocellular carcinomas(HCCs), hemangiomas, and metastases on three-phase images with spiral CT for differential diagnosis. MATERIALS AND METHODS: Three-phasespiral CT scan was performed in 73 patients with hepatic masses. CT scanning was performed with a table speed of 10mm/sec, section thickness of 10mm, and a reconstruction interval of 5mm, 100-150ml of contrast medium was injected intravenously with an automatic injector at a rate of 2-3mL/sec. CT scans were obtained at 30, 70 and 180 seconds after the start of contrast material injection. RESULTS: The enhancement patterns of 136 lesions in 53 patients with HCCs were as follows : 47 lesions(35%) were totally high and 55(40%) were mixed in the early phase ;30 lesions(22%) were mixed and 66(49%) were totally low in the portal phase ; and 105 lesions(78%) were totally low in the delayed phase. In hemangiomas of 23 lesions in 15 patients, 7 lesions(30%) were peripherally high and11(48%) were totally low in the arterial phase ; 4 lesions(17%) were totally high and 12(53%) were peripherally high in the portal phase ; 10 lesions(42%) were totally high and 4(18%) were peripherally high in the deayed phase. In metastatic liver mali gnancies of 42 lesions in 5 patients, 13 lesions(31%) were peripherally high and 22(52%) were totally low in the arterial phase ; 32 lesions(77%) were totally low in the portal phase, and 35(83%)were totally low in the delayed phase. CONCLUSION: Three-phase spiral CT scanning is a useful diagnostic methodin the differential diagnosis of hepatic masses including HCCs, hemangiomas, and hepatic metastases.