Hepatitis C virus (HCV) infection is aetiologically very closely associated with hepatocellular carcinoma (HCC). World-wide, hepatitis B virus infection is the predominant aetiological factor in developing countries, whereas in industrialized countries, HCV has a far more important role in hepatocarcinogenesis. The varying weights of the aetiological role of HCV infection are compared among countries. The speed of progression of chronic hepatitis C to cirrhosis, thenceforth to HCC, and certain discrepancies between an American study and the Japanese experience are described. The reason for the recent surge of HCV infection and subsequent increase in the incidence of HCC is also discussed. The genetic mechanism of HCV-induced hepatocarcinogenesis is still poorly understood.