Autoimmune hepatitis is a chronic liver disease putatively caused by loss of tolerance to hepatocyte-specific autoantigens. It is characterized by female predilection, elevated aminotransferase levels, autoantibodies, increased γ-globulin or IgG levels and biopsy evidence of interface hepatitis. It is currently divided into types 1 and 2, based on expression of autoantibodies. Autoantigenic epitopes have been identified only for the less frequent type 2. Although autoimmune hepatitis occurs in childhood, this review focuses on disease in adults. In the absence of pathognomonic biomarkers, diagnosis requires consideration of clinical, biochemical, serological and histological features, which have been codified into validated diagnostic scoring systems. Since many features also occur in other chronic liver diseases, these scoring systems aid evaluation of the differential diagnosis. New practice guidelines have redefined criteria for remission to include complete biochemical and histological normalization on immunosuppressive therapy. Immunosuppression is most often successful using prednisone or prednisolone and azathioprine; however, the combination of budesonide and azathioprine for non-cirrhotic patients offers distinct advantages. Patients failing standard immunosuppression are candidates for alternative immunosuppressive regimens, yet none of the options has been studied in a randomized, controlled trial. Overlap syndromes with either primary sclerosing cholangitis or primary biliary cirrhosis occur in a minority. Liver transplantation represents a life-saving option for patients presenting with acute liver failure, severely decompensated cirrhosis or hepatocellular carcinoma. Transplant recipients are at risk for recurrent autoimmune hepatitis in the allograft, and de novo disease may occur in patients transplanted for other indications. Patients transplanted for AIH are also at risk for recurrent or de novo inflammatory bowel disease. Progress in our understanding of the immunopathogenesis should lead to identification of specific diagnostic and prognostic biomarkers and new therapeutic strategies.