The diagnosis of autoimmune hepatitis (AIH) relies on the exclusion of viral, metabolic, genetic, and toxic etiologies of chronic hepatitis or hepatic injury. There are few parameters that positively predict the presence of AIH. Autoantibodies have been intensively evaluated in this respect and have led to the classification of AIH into three serological subgroups: antinuclear and smooth muscle antibody-positive (ANA/SMA, type 1), liver-kidney microsomal antibody-positive (LKM-1, type 2), and soluble liver antigen/liver-pancreas antigen antibody-positive (SLA/LP, type 3) AIH. Although there are few clinical implications resulting from this classification, autoantibody profiles indicate that AIH is a heterogenous group of entities. The molecular characterization of B cell autoimmunity has led to the identification of major phase I and phase II metabolic enzymes as well as structural and functional components of the cell nucleus as immunologic targets. Autoantibodies and their corresponding autoantigens are intensively studied to provide clues to the understanding of disease initiation, tissue specificity, and propagation of hepatic autoimmune diseases.