Autoimmune hepatitis (AIH) is a chronic necroinflammatory liver disorder associated with hypergammaglobulinemia and circulating autoantibodies. Two patients previously diagnosed with multiple sclerosis who developed AIH are reported. One patient showed acute presentation with fulminant hepatic failure requiring liver transplantation. Serum autoantibodies were negative in both patients but a characteristic clinical course in the first patient as well as the hepatic histological features with typical pathological changes of AIH in both patients and a score compatible with AIH established the diagnosis.