Backgroung/Aims : The prognosis of primary hepatocellular carcinoma is extremely poor because of its large size, portal vein thrpombosis, extrahepatic metastasis and underlying liver cirrhosis. The aim, of this study is to evaluate the usefulness of ultrasound screening test for early detection of hepatocellular carcinoma in high-ridk populations. Methods : We analysed 119 patients who were diagnosed with hepatocellular carcinoma by ultrasonography screening test in Yonsei University Severance Hospital from the period of January 1990 to December 1996. Result : The mean follow-up duration to the diagnosis of hepatocellular carcinoma was 30 months (range 3-75). The number of patients with single lesion was 89(75%). The mean diameter of the tumor was 3.0 cm (range 1-10) , 82 patients (70%) had masses measured less than 3cm in diameter. The Number of patients with elevated serum alphafetoprotein level above 400ng/ml was 29(25%). The median survival was 28 months in screening group, significant compared with 7 months in control group (p<0.001). Conclusions : Ultrasound follow-up in high-ridk group of hepatocellular carcinoma mede it possible to detect small tumors in a high percentage of cases. This may lead to an increase in the number of potentially curable tumors and hence an increase in the overall survival rate. So ultrasound screening test is important in the high-ridk group of hepatocellular carcinoma.