A 19-year-old woman presented with clinical manifestations of sudden, fulminant thrombotic thrombocytopenic purpura associated with autoimmune hepatitis and autoimmune thrombocytopenic purpura. Although thrombotic thrombocytopenic purpura may, rarely, be associated with systemic lupus erythematosus and other autoimmune diseases, to our knowledge, the syndrome has never been described in association with autoimmune hepatitis. In this patient, too, the etiology of thrombotic thrombocytopenic purpura associated with autoimmune disease remains elusive. The patient was treated with corticosteroid, which brought about no improvement in her condition, and she died of multiorgan failure. Diagnosis is challenging, but prompt diagnosis is necessary because thrombotic thrombocytopenic purpura is a life-threatening syndrome whose prognosis has been improved significantly by early plasmapheresis treatment.