We reviewed 12 patients who had Kikuchi-Fujimoto disease (KFD) and presented with prolonged fever and lymphadenopathy. The clinical and laboratory aspects of the patients confirmed by excisional lymph node biopsy were analyzed. The mean age of the children was 11.0 +/- 3.0 years (range: 6-15 years). The male-to-female ratio was 1.4:1. The median duration of fever before admission and the total duration of fever was 13 days (range: 7-65 days) and 19.5 days (range: 9-75 days), respectively. One patient had supraclavicular lymphadenopathy, 10 had cervical involvement, and 1 had axillary lymphadenopathy. All of the histologic findings of the lymph node biopsies showed the characteristic findings consistent with KFD, such as paracortical necrosis with karyorrhexis and an increase in the number of phagocytic histiocytes and atypical lymphocytes. As for the laboratory findings, leukopenia (3600 +/- 900 per mm3), anemia (hemoglobin 11.4 +/- 1.2 g/dL), an elevated erythrocyte sedimentation rate (44 +/- 18 mm/hour), and a relatively low C-reactive protein level (1.3 +/- 1.1 mg/dL) were noted. Eight patients received conservative therapy with antipyretics, and 3 patients were treated with prednisolone. KFD is a rare disease yet should be considered in the differential diagnosis for older children with prolonged fever and lymphadenopathy.