PURPOSE: To determine the enhancing patterns of hepatocellular carcinoma(HCC) and the difference of enhancing patterns according to the tumor size, using spiral CT. MATERIALS & METHODS: We reviewed 213 lesions in 76patients who had been clinically or histopathologically diagnosed as HCC sufferer. The tumors were divided into three groups, according to size(&3 cm, 3-5cm and >5 cm). The enhancing patterns of tumor and capsule in the earlyand delayed phase were analysed. The enhancing patterns of the tumor were divided into five types(high, peripheralhigh, mixed, iso and low attenuation) in the early phase and four types(central high, mixed, iso, and low attenuation) in the delayed phase. The enhancing patterns of the capsule were divided into three types such asiso, low and high attenuation. RESULTS: High attenuating lesions in the early phase were as follows : below 3cm 72% ; 3-5cm., 60% ; above 5cm., 49%. Mixed attenuating lesions in the early phase were as follows : below 3cm., 1%; 3-5cm., 22% ; above 5cm., 36%. Thus, most HCCs were high attenuation type in the early phase, but as the tumorbecame larger, less high attenuation and more mixed attenuation was demonstrated(p<0.01). There was no difference of enhancing patterns according to the tumor size in peripheral high, iso and low-attenuating lesions. In the delayed phase most of the hepatomas appeared as totally hypodense lesions. For capsules, the results were as follows : below 3cm., 20% ; 3-5cm.,58% ; above 5cm., 73%. As the tumors became larger, more capsules were demonstrated(p <0.01). The capsules were visualized as iso or low attenuating rim in the early phase and high attenuating rim in the delayed phase. CONCLUSIONS: To determine the enhancing patterns of HCC using spiral CT is considered to be helpful in the diagnosis of HCC.