Chronic viral hepatitis B and C infections are the diseases associated with the highest risk for developing hepatocellular carcinoma. These infections are prevalent worldwide. Many factors modulate the risk of developing hepatocellular carcinoma in chronic viral hepatitis, such that the assessment of an individual patient’s risk is a complex consideration. The presence of cirrhosis is the most important risk factor for the development of hepatocellular carcinoma in both hepatitis B and C. Thus, one of the major mechanisms for hepatocarcinogenesis in these infections is mediated in some way through chronic liver injury. In addition, there is evidence to support a direct oncogenic effect of both HBV and HCV, although the evidence is weaker for HCV. Other risk factors for hepatocellular carcinoma in chronic viral hepatitis include: geographical location; whether in a high or low prevalence area; host factors, particularly sex and age; and specific viral factors. In chronic hepatitis B without cirrhosis the risk of hepatocellular carcinoma is 0.5%-0.8% per annum, increasing to 1.4-2.5% in cirrhotic patients. In chronic hepatitis C with cirrhosis the risk is 1.4-2.5% per annum, while in Australia, patients with hepatitis C rarely develop hepatocellular carcinoma in the absence of cirrhosis.