In 1992, the Falk Symposium No. 70 dealt with the topic Immunology and Liver . At that time, basic mechanisms of immunology as well as immunopathogenetic mechanisms in viral and autoimmune liver diseases were discussed. Seven years later, the Falk Symposium No. 114, held in Basel, Switzerland, October 20-21 1999 (Part I of the Basel Liver Week 1999), focused on immunology in autoimmune liver diseases. In the first section of this text, basic mechanisms of autoimmunity are presented, including the relevance of superantigens and the role of apoptosis. A further topic is the latest developments concerning animal models for autoimmune diseases. Drug- and hepatitis-virus induced immune mediated liver diseases may serve as models for nonhepatic immune mediated disorders. DNA technology has increased our knowledge of the immunogenetic background of autoimmune liver diseases. Among the cholestatic immune mediated liver diseases, significant progress has been made concerning primary biliary cirrhosis, in particular regarding the identification of mitochondrial antigens and the characterization of the immune reactions directed at them. The involvement of infectious agents in PBC as well as the definition of overlap syndromes is a particular focus for basic and clinical research in this area. Concerning the therapy of autoimmune liver diseases, corticosteroids and azathioprin remain the state of the art for autoimmune hepatitis, while bile acids have become well established in treatment of primary biliary cirrhosis as well as primary sclerosing cholangitis. New drugs in the future will include topical steroids such as budesonide and new immunosuppressive agents like mofetil/mycophenolate.