Kikuchi-Fujimoto's disease (KFD), or histiocytic necrotizing lymphadenitis, is a rare benign and self-limiting disease. KFD are confused with systemic autoimmune disease as they present with localized lymphadenopathy, fever, fatigue, arthritis, leukopenia. Furthermore as KFD can occur associated with other autoimmune disease, we need to diagnose carefully. Here, we describe a case of 27-year-old female patient, diagnosed as KFD, who subsequently developed adult onset Still's disesase (AOSD). As far as we know, this is the first case of KFD with AOSD in Korea.