Hepatitis B virus (HBV) is the major cause of acute and chronic hepatitis, leading to progressive development of necroinflammatory changes in the liver, which can result in cirrhosis and hepatocellular carcinoma. Although the development of an effective vaccine to prevent HBV infection has shown promising results and should lead to its eventual eradication, antiviral chemotherapy remains the only effective method to prevent the progression of the disease in chronic carriers. Therefore, the development of new antiretroviral agents active against HBV is needed. HepG2 cells have an epithelial morphology and are thought to be a very useful model to study HBV virus replication via transfection. Cells are also used for cancer and apoptosis studies (in particular signalling pathway studies).