In Japan, approximately 30,000 patients died of hepatocellular carcinoma (HCC) in 2003. Ten percent had hepatitis B virus infection and 80% had hepatitis C virus (HCV) infection, indicating that viral hepatitis accounted for >90% of cases of HCC. In comparison, only 3% (1.5%, hepatitis B virus; 1.5%, HCV) of the general population is infected with these viruses. We treated 1238 patients between 1992 and the end of 2003 by means of percutaneous tumor ablation (PTA): 524 patients, by percutaneous ethanol injection therapy (PEIT); 85 patients, by percutaneous microwave coagulation therapy; and 629 patients, by radiofrequency ablation (RFA). Three-, 5-, 7-, and 10-year survival rates of the 1238 patients were 69%, 50%, 34%, and 19%, respectively. When limited to tumors </=3 cm in diameter and </=3 in number of cancer nodules (3-3 rule), 5-year survival rates reached 64.7% for PEIT. However, to achieve a 40% survival rate in year 5 after PEIT, the indication for treatment can be expanded to a 4 (size)-3 (number) rule or 5 (size)-1 (number) rule. The recent introduction of RFA may further change the rules. HCV-related HCC generally develops on the background of advanced fibrosis/cirrhosis. An issue of much concern is that it may subsequently recur in a location other than that of the primary lesion. We initiated a prospective controlled study to evaluate treatment with PTA and interferon. Results suggest that if the virus is eradicated, a 5-year survival rate as high as 80% can be expected.