BACKGROUND: Endobronchial tuberculosis(ET) is known to affect frequently young female and serious complication like bronchial stenosis would occur if early diagnosis and treatment for ET is not performed immediately. But ET shows normal chest roentgenogram in about 10% of patients, and is often confused with bronchial asthma because ET presents clinical features like cough, dyspnea, wheezing in history and physical examination. The pulmonary function test(PFT) feature of ET is not well known, but when we consider the fact that ET is pathophysiologically different from bronchial asthma, if there is any feature of PFT in ET, and we know it, PFT will be very helpful for diagnosis and follow up of ET. METHODS: We performed both PFT and bronchoscopy in 68 ET patients who visited Boramae hospital, and were confirmed as ET by bronchoscopic biopsy and were followed prospectively from November 1991 to March 1995. After history taking and physical examination, we performed chest roentgenogram, complete blood count, sputum AFB stain and culture, and also performed PFT before anti-tuberculosis chemotherapy. PFT was classified as restrictive, if only FVC was reduced below 80%, and obstructive, if only FEV1 was reduced below 75%. In the case of both FVC and FEV1 were reduced, PFT was classified as restrictive if FEV1/FVC was greater than 75%, and mixed if FEV1/FVC was reduced below 75%. We repeated the PFT and bronchoscopy for 68 ET patients who were proven by biopsy in the first month and sixth month after starting anti-tuberculosis chemotherapy, and studied the feature and change of PFT of the ET and the relation between PFT and the bronchoscopic finding, and obtained following results. RESULTS: 1) Number of male patients was 12, and that of female patient was 56, and mean age was 35.4 +/- 17yr.(17-74yr). Clinical symptom was in the order of cough(86.8%), dyspnea(63.2%), fever (17.6%) and hemoptysis (10.3%), and the wheezing and stridor were audible among the 40 patients(58.4%) in the physical examination. 2) Hemoglobin level was below 12g/dl among 25 patients (36.8%), and WBC level was above 10,000/mm3 among 9 patients(13.2%) and ESR was above 20 among 46 patients (67.6%) and AFB stain and culture were positive among 50 patients(73.5%). 3) The dominant roentgenographic finding of ET was fibronodular feature in 35 patients(51.5%), pneumonic feature in 14 patients (20.6%), collapse in 11 patients(16.2%), mass-like lesion in 3 patients(4.4%), cavitary lesion in 2 patients(2.9%), and normal in 3 patients(4.4%). 4) PFT feature at the time of diagnosis of ET was normal in 16 patients(23.5%), restrictive pattern in 32 patients (47%), obstructive in 4 patients(5.8%), and mixed in 14 patients(23.5%). So restrictive pattern was the dominate feature of ET. 5) The PFT feature was little correlated with the gross finding of bronchoscopy, but the change of PFT during treatment of ET showed relatively good correlation with the change of bronchoscopic finding. 6) FVC(2.30L vs. 2.61L) and FEV1(1.74L vs. 2.06L) increased significantly (p < 0.01), but FEV1/FVC(82% vs. 83%) and PEF(3.45L/sec vs. 3.95L/sec) did not change significantly after 1 month of treatment (p > 0.01), and there was no significant change among all parameters during first and sixth month of treatment(p > 0.01). CONCLUSION: PFT may be useful in the diagnosis and treatment follow up of ET but further study would be needed to confirm it.