Purpose: High levels of bone morphogenetic protein (BMPs) have been reported in patients with lung cancer. This study was conducted to assess correlations between serum BMP-2 levels and prognostic outcome in patients with non-small-cell lung cancer (NSCLC). Methods: Blood samples from 84 patients with advanced NSCLC and 42 healthy controls were analyzed and quantitated for serum BMP-2 levels before and after two cycles of chemotherapy using a commercially available ELISA kit. Results: The median level of BMP-2 was 146.9 pg/ml in patients with NSCLC vs. 87.7 pg/ml in healthy controls (P<0.01). A significant correlation was observed between pretreatment serum BMP-2 level and ECOG PS, disease stage and number of organs with metastases (P<0.05). Serum BMP-2 level decreased significantly in patients who achieved objective response after two cycles of chemotherapy. Multivariate analysis showed that increased BMP-2 level and advanced clinical stage were significantly correlated with poor prognosis. Conclusion: Thes erum BMP-2 level is positively correlated with clinical stage, ECOG PS and metastatic burden and may serve as an independent negative predictor for prognosis. Decreased BMP-2 after chemotherapy could be a reliable marker for efficacy of treatment.