Chronic viral hepatitis is discussed here in a multidisciplinary approach. The editors' goal was to assemble contributions from clinicians, laboratory physicians, epidemiologists, pathologists, and molecular biologists to provide a synopsis of all the important aspects of this disease. A key element in the chronic evolution of viral hepatitis is the persistent coexistence of a cytotoxic immune response and viral gene expression which is discussed in eleven articles on immune pathogenesis. The oncogenicity of hepatitis B virus at the molecular level and of hepatitis C virus at the epidemiological level is discussed in two chapters. The application of PCR for the detection of hepatitis viruses and their variants is a major topic of both practical and theoretical interest. The clinical significance of newly developed serological assays for diagnosis and prevention is discussed in depth by specialists from clinics, transfusion centers and virological laboratories. The therapy of chronic viral hepatitis is still unsatisfactory, but some slow progress is described in several articles. Furthermore, the volume has a special chapter on the often neglected topic of chronic hepatitis in childhood.