BACKGROUND: Transbronchial lung biopsy (TBLB) is a relatively simple and convenient procedure to obtain lung tissue in from a patient, with with diffuse or localized lesion on chest radiographs, whose disease cannot be diagnosed through routine tests. The authors tried to evaluate the diagnostic value of TBLB, especially, the concordance between CT scan and TBLB with respect to the location of the lesion, and and diagnostic yield according to tumor-bronchus relationship. METHOD: We reviewed the medical records, plain chest films, and chest CT scans of 278 patients who underwent TBLB at Kyungpook National University Hospital between January 1996 and June 1998. RESULTS: One hundred and sixteen (41.7 %) patients were diagnosed by TBLB. Diagnostic yield of TBLB in of malignant tumor tumors tended to be higher than that of benign disease diseases (64.7 % versus 53.9 %, p=0.09). Of primary lung cancers, TBLB was more diagnostic in adenocarcinoma and small-cell carcinoma than the rest other cell types (p<0.01) and, of benign diseases, more diagnostic in tuberculosis than in non-tuberculous diseases (p<0.05). According to the location of tumor, there was There was no significant difference in the diagnostic rate according to the location of the tumor. The diagnostic rate tended to increase with the size of tumor (p=0.06). In benign disease, there There was no difference in the The diagnostic rate of TBLB did not differ according to the pattern of lesion in benign diseases(.) but in malignant disease, However, in malignant diseases TBLB was more diagnostic in diffuse/multiple nodular lesion lesions than in localized lesion lesions (p<0.05). According to the tumor-bronchus relationship, TBLB was more diagnostic in type I/II groups than the rest in other types. CT scan and TBLB showed a strong correlation with respect to the localization of the lesion (gamma=0.994, p<0.01). CONCLUSION: The above results showed show that TBLB is useful in the diagnosis of lung disease. CT scan and TBLB showed a strong correlation in deciding in determining the location of the lesion. Diagnostic yield of TBLB is higher in the lesion lesions with 'bronchus sign' (type I and II). It is anticipated that (delete) TBLB and other diagnostic methods such as transthoracic needle aspiration have complementary role in diagnosing lung disease. are expected to complement one another in the diagnosis of lung diseases.