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 endostatin expression and clinical prognosis as well as pathophysiological characteristics. Methods The samples of serum and BALF were obtained from 57 patients with untreated primary lung cancer ( lung cancer group) and 27 patients with benign pulmonary diseases (control group). The levels of endostatin were analyzed by enzyme-linked immunosorbent assay (ELISA). Results The expression of endostatin in serum and BALF in lung cancer group was significantly higher than that in control group ( P ＜0. 01 ). The levels of endostatin in serum and BALF in late-stage ( stage Ⅲ or Ⅳ ) lung cancer patients were significantly higher than that in early-stage ( stage Ⅰ or Ⅱ , P ＜ 0. 01 ).The expression of endostatin both in serum and BALF were significantly higher in adenocarcinoma patients than that in squamous cell carcinoma or SCLC patients. Endostatin concentrations in BALF and serum were significantly greater in patients with lymph node and distant metastasis than those patients without. the expressions of endostatin in serum were closely related to that in BALF in patients with lung cancer ( P = 0. 000). Conclusion The expression of endostatin in serum and in BALF is higher in lung cancer than benign pulmonary diseases and it was associated with TNM stage, lymph node metastasis and clinicopatholgical variables. The level of endostatin in BALF is higher than that in serum and may be used as a significant marker to direct clinic therapy and estimation of prognosis.