Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Several risk factors for HCC development have been identified, including cirrhosis, hepatitis B virus (HBV) infection, and hepatitis C virus (HCV) infection. With regard to cirrhosis, multivariate analysis indicates that alcohol abuse, HBsAg positivity, and anti-HCV seropositivity are independent variables associated with an increased risk for HCC in the cirrhotic patient. A close relationship between chronic HBV infection and HCC has been established by epidemiological studies and laboratory investigations. Evidence indicates that HCV also plays a leading role in development of HCC. Most patients with HCV-related HCC develop the tumor as a consequence of long-standing infection accompanied by chronic and progressive liver damage. In our study of 290 consecutive patients with cirrhosis, patients with persistently elevated or fluctuating ALT levels had a significantly greater rate of HCC development. The mechanism of HCC development in HCV infection remains to be elucidated. The annual cumulative risk of developing HCC is approximately 1% in patients without cirrhosis at inclusion and 3-10% in those with cirrhosis, depending on the stage of cirrhosis and presence of etiological cofactors. Although some evidence suggests that patients infected with the HCV genotype 1b are at increased risk for development of more severe liver disease, including HCC, results of our prospective study do not support a difference between cirrhotic and noncirrhotic patients in terms of the natural course of cirrhosis and the rate of developing HCC based on genotype. Strategies to prevent HCV-related HCC include blood screening and treatment of chronic HCV infection with interferon-alpha. Recent studies suggest that interferon-alpha treatment may prevent the development of HCC in HCV infection. Further research is warranted.