Hepatitis C virus (HCV) infection is now recognized to be a major risk factor for hepatocellular carcinoma (HCC), evidenced by finding both antibody to HCV (anti-HCV) and HCV RNA in serum of a substantial proportion of patients with HCC around the world and by the progression of liver disease to cirrhosis and HCC in individual patients infected with HCV. There seems to be an incubation period of two to three decades on average in most cases of HCV-related HCC. HCV infection usually results in development of HCC via cirrhosis, although the possibility of direct carcinogenic effects of HCV is still under study. Possible additional risk factors include infection with HCV genotype 1b, alcohol consumption, and co-infection with the hepatitis B virus. Estimates of the development of HCC among patients with cirrhosis of all types range between 1% and 4% per year. Assuming that 20% of patients with chronic hepatitis C go on to develop cirrhosis over a 10-year period, between 1.9% and 6.7% of all patients with chronic hepatitis C can be expected to develop HCC over the first two decades of infection. Although tests are available to screen for early HCC, the results of treating these small tumors have been disappointing. Thus, it is imperative that cost-effective means be developed for screening and prevention of HCV-related HCC.