Abstract: Polymerase chain reaction(PCR)was applied to detect DNA of mycobacterium tuberculosis(TB)in 78 clinical samples. Methods: For each sample, TB-PCR, the positive rate of acid fast staining, tuberculin skin test and tuberculous antibody were made. The results of PCR were compared with those of conventional procedures and clinical diagnosis standard. Results: It was found that the positive rate of acid-fast staining, tuberculin skin test, tuberculous antibody and PCR were 3.85%、17.95%,11.54% and 46.15% respectively in 78 tuberculous samples. The sensitivity of PCR was much higher than the former diagnostic procedures. Conclusions: up to now, the results showed that the PCR was a valuable detective tool for diagnosis and differential diagnosis of tuberculosis. Diagnosis of tuberculousis still need to be determined by the patient's chlinical menfestions and others methods.

Key words: polymerase chain reaction(PCR), mycobacterium tuberculosis, pulmonary tuberculousis