A 15-year-old boy was hospitalized with a 1-month history lumbago and fever. His family history was noncontributory for tuberculosis, and the findings of the physical examination were normal. The sedimentation rate and C-reactive protein level were 55 mm/hour and 48 mg/l, respectively. The result of a purified protein derivative test was 11 x 10 mm. Results of other tests, including rheumatologic studies, serum agglutination for brucellosis, chest radiography, abdominal ultrasonography, and myelography, were normal. The bone biopsy revealed chronic active inflammation. Mycobacterium tuberculosis was not cultured from clinical specimens. However, the patient's symptoms improved after antituberculosis drugs were begun.