Tuberculosis is commonly observed as a cause of necrotizing granulomatous inflammation of cervical lymph nodes. However, Ziehl-Neelsen(ZN) stain for acid-fast bacilli(AFB) is often negative. In patients with cervical lymph node enlargement, tuberculous lymphadenitis should be included in the differential diagnosis, and an accurate diagnosis leads to an appropriate treatment. A repetitive DNA sequence specific for Mycobacterium tuberculosis was amplified by using the nested polymerase chain reaction(PCR) technique from fresh or paraffin-embedded biopsy specimens of 34 patients with cervical lymph node enlargement which was compatible with tuberculous lymphadenitis on hematoxylin-eosin stain. Ziehl-Neelsen stain was positive for AFB in 21 cases and revealed no organisms in 13 cases. A 188-base-pair fragment, specific for the Mycobacterium tuberculosis PCR product was obtained from all 34 cases. Comparing ZN stain for AFB and PCR results, we confirm that the PCR method is more powerful and more sensitive than ZN stain in the etiological diagnosis of tuberculous lymphadenitis. This report demonstrates the practical use of PCR for rapid detection of Mycobacterium tuberculosis, particularly in cases difficult to diagnose conventionally with ZN stain.