Chronic active Epstein-Barr virus infection (CAEBV) is characterized by chronic or recurrent infectious mononucleosis-like symptoms, such as fever, extensive lymphadenopathy, and hepatosplenomegaly. A 44-year-old women visited our ENT clinic with a four-month history of fever and throat pain. She was diagnosed as having CAEBV based on the findings of fever, liver dysfunction, lymphadenopathy, pharyngeal ulcer, the titer for IgG to the EBV capsid and pathological findings. The whole-blood EBV DNA levels were high and above 3.7 x 10(3) copies/mL. After administration of intravenous predonine (1000 mg/day for 3 days) and oral predonine (1.5 mg/kg. 60 mg/day), the liver dysfunction and pharyngeal ulcer improved. Since the prognosis is poor in adult cases of CAEBV, chemotherapy is scheduled for this case.