In patients with cervical lymph node swelling, prompt differential diagnosis of tuberculosis leads to an appropriate treatment. A method based on DNA amplification and hybridization for the rapid detection of Mycobacterium tuberculosis was used for demonstrating its specific DNA in cervical lymph nodes biopsied from seven patients. The DNA specific for Mycobacterium tuberculosis was detected in 5 patients. Four of them were histologically diagnosed as tuberculous lymphadenitis. In another case with necrotizing lesions but without granulomatous reactions, culture method subsequently revealed a positive result. In other 2 cases, the diagnosis of tuberculosis was promptly excluded by both this method and conventional methods (histologic diagnosis/direct microscopy). The rapid detection of Mycobacterium tuberculosis by amplification of mycobacterial DNA is helpful particularly in differential diagnosis of cervical lymphadenopathy.