Autoimmune hepatitis affects all ages with a peak incidence in preadolescent girls. The pathogenesis of autoimmune hepatitis has not been defined. Susceptibility, clinical manifestations, and treatment outcomes are affected by environmental factors, individual immunoregulatory responses, genetic factors, age and gender. An international panel has developed diagnostic criteria for autoimmune hepatitis, and a scoring system to assess the strength of the diagnosis has also been proposed. This article discusses the diagnosis and treatment of the three types of autoimmune hepatitis proposed based on characteristic autoantibody profiles, as well as de novo autoimmune hepatitis, a new type of autoimmune hepatitis that has been recently described in liver transplant recipients without previous autoimmune disease.