A 66-year-old female presented with acute illness of severe hepatic dysfunction. She had a past history of chronic hepatitis of low disease activity. After admission and clinical investigation including liver biopsy, it showed an underlying chronic liver disease suggestive of autoimmune hepatitis (AIH) with early liver cirrhosis. Together with other clinical features, this patient was diagnosed as definite AIH type 1 by using the IAIHG (International Autoimmune Hepatitis Group) criteria. During this episode, superinfection by Epstein-Barr virus (EBV) was evidenced by positive PCR (polymerase chain reaction) test, and serial changes of EBV VCA IgM and IgG tests. Severe hepatic impairment was evidenced by markedly elevated AST level 3090 IU/L, high bilirubin level 26.4 mg/dL, and presence of ascites. The patient gradually recovered and liver function improved in agreement with the decline of EBV VCA titers. Immunosuppressive therapy resulted in further improvement of the aminotransferases levels. This is an unusual case of EBV superinfection on pre-existing AIH with early cirrhosis, which caused enhancement of the autoimmune disease process and resulted in severe hepatic decompensation and jaundice. We herein describe the case and briefly review the literature.