BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) is the 3rd most common cancer. The annual incidence is over 10,000 cases in Korea. While hepatitis B virus is major cause of Korean HCC, the impact of alcoholic liver disease is a rising trend. The 5-year survival rate of HCC is only 9.6%, mainly due late diagnosis, tumor biology and underlying chronic liver diseases. Because almost eighty percent of HCC is diagnosed in late, not early stages, a nationwide surveillance program to screen high risk groups (HBV or HCV carriers or liver cirrhosis, over 40 years old) was launched last year and a practice guideline, with special emphasis on advanced stage HCC was formulated. METHODS: Forty-five experts from KLCSG and the National Cancer Center participated in a special committee to develop a practice guideline for HCC. Based on scientific evidence, the consensus was made for diagnosis and treatment strategy after considering the medico-social situation in Korea. RESULTS: Required and optional tests and clinical (non-invasive) diagnosis criteria for HCC are identified. The first decision, based on both Child-Pugh score and modified UICC tumor staging, is to determine operability. The second decision, to determine resectability, is based on localization of the tumor and residual liver function. Chemoembolization or local ablation therapy is allowed for resectable tumors in certain conditions, such as at borderline risk or non-invasively diagnosed. Unresectable tumors are classified into either a group with inadequate residual liver functions or the another group with extensive or macrovascular invasion or distant metastases. Indications of liver transplantation, chemoembolization, local ablation, radiation therapy and chemotherapy for unresectable HCC are presented. CONCLUSIONS: This guideline is expected to be useful for clinical management of, and research for HCC patients.