PURPOSE: The sheath of tendon is uncommon site of tuberculous involvement as compared to other parts of the body. Especially, tuberculous tenosynovitis affecting flexor tendon of the hand is a rare condition. In recent years, furthermore, the incidence of tuberculosis is increasing in our country. Tuberculous tenosynovitis is a chronic, slowly destructive disease, which is difficult to diagnosis before operation, but can be definitively diagnosed by the pathologic microscopic examination. Early detection and surgical excision combined with antituberculous medication is important. We report a rare case of tuberculous tenosynovitis of the flexor tendon of the hand. METHODS: A 12-year-old woman presented with a painless, nontender mass on palmar side between distal interphalangeal joint and proximal area of metacarpophalangeal joint of the left third finger. We had surgical excision of the involved flexor tendon sheath and studied histopathologically. RESULTS: The histopathological findings were chronic granulomatous inflammation with caseating necrosis consistent with tuberculosis. We started antituberculous medication. CONCLUSION: Tuberculous tenosynovitis is a rare condition, especially involving on the flexor tendon of the hand. But because of increasing tendency of tuberculosis, it is important to differentiate it from other tumors of the hand.