Abstract: Objective 　To evaluate the expression of endostatin in bronchoalveolar lavage fluid (BALF) and serum in patients with lung cancer. And to analysis the relationship between the levels of it and clinical features as well as pathophysiological characteristics. Methods 　The samples of serum and BAL F were obtained from 47 patient s with untreated primary lung cancer and 18 patients with benign pulmonary diseases. The levels of endostatin were analyzed by enzyme-linked immunosorbent assay ( ELISA) . Results 　The expression of endostatin in serum was (131. 71 ±50. 32) ng/ ml and in BALF was (502. 56 ±302. 00)ng/ ml in patient s with lung cancer. And the expression of endostatin in patient s with benign pulmonary diseases was (85. 86 ±36. 86) ng/ ml and (279. 49 ±135. 17) ng/ ml, respectively ( P < 0. 01), there was significantly difference between them. The levels of endostatin in serum and BALF in advanced stage lung cancer patient s were higher than those of early stage patients. In adenocarcinoma patients was significantly higher than that in patients with squamous cell carcinoma and SCLC in serum and BAL F. Endostatin concent rations in BALF and in serum were significantly higher in patients with lymph node and distant metastasis than those patient s with no metastasis. The expression of endostatin in serum was closely related to that in BAL F in patients with lung cancer ( P = 0. 000) . Conclusion 　The detection of endostatin in serum and in BALF may be helpful to distinguish the lung cancer from benign pulmonary diseases and to reveal the biological behaviors of lung cancer well.