Viral hepatitis, by either hepatitis C virus (HCV) or hepatitis B virus (HBV), is the dominant cause of hepatocellular carcinoma (HCC). This is to say that HCC may be prevented by controlling viral infection. Horizontal transmission of HCV has become obsolete owing to the discovery of the virus. Vertical transmission of HBV during delivery has been effectively prevented by vaccination and immunization of neonates. The efficacy of interferon therapy against HCV was recently much improved. We now possess several powerful antiviral drugs against HBV. There has been progress also in the treatment of HCC, and together with advances in diagnostics facilitating HCC detection at an early stage, tumor nodules can often be completely removed either by medical ablation or surgical resection. Nevertheless, recurrence of HCC after apparently curative treatment is extraordinarily frequent, since the remaining liver is still at a particularly high risk of HCC. An effective treatment of HCC should include measures to control de novo carcinogenesis.