To the editor: The recent report on "Real-time polymerase chain reaction (PCR) assay for the diagnosis of pulmonary tuberculosis" is very interesting¹. Kim et al.¹ noted that "Real-time PCR from selective bronchoscopic aspirates enhances the diagnostic yield much more when added to sputum examination." In fact, polymerase chain reaction assay for tuberculosis (TB) is considered new and useful diagnostic test. However, there are some concerns on this assay. First, false-positive of the test can be seen in cases with "treated or old lesion from pulmonary TB²." Second, the low sensitivity of the test can be seen^1,2,3. In fact, there are many possible causes of low sensitivity including to type of specimen transfer and duration time, the DNA extraction procedure, DNA amplified process, DNA extraction, and reproducible technique². Finally, the cost effectiveness of the test is the topic for further studied.