Kikuchi's disease(histiocytic necrotizing lymphadenitis) is characterized by lymphadenopathy in young patients below 30 years old, and persistent fever, lymphopenia and splenomegaly are concomitantly developed in many cases. So, it has been confused with lymphoma, SLE, and tuberculosis, and has easily led to inappropriate diagnostic procedures and administration of drugs. Many reports have indicated that Kikuchi's disease should be added to the list of causes of FUO in the setting of lymphadenopathy, and recommended early lymph node biopsy to distinguish from lymphoma, SLE, and tuberculosis to avoid unnecessary treatments. We experienced a case of subacute necrotizing lymphadenitis in a 14-year-old boy who presented with persistent high fever, productive coughing and cervical lymphadenopathy for about 1 month. Initially, diagnostic workup was done to look for the causes of FUO in vain. Finally, we confirmed diagnosis by histopathological findings of lymph node biopsy and detected latent gene of EBV in the biopsied specimen using in situ hybridization.