Chronic infections with hepatitis B (HBV) and hepatitis C (HCV) virus are worldwide problems often leading to the development of chronic liver disease and hepatocellular carcinoma. Genetic immunizations with DNA encoding for structural and nonstructural proteins of HCV and HBV in experimental mice generate a broad base CD4+ and CD8+ cellular immune response which may be required for viral clearance from the host. DNA based immunization is a promising antiviral approach for the development of therapeutic and prophylactic vaccine against HBV and HCV.