Objective: To examine the expression of hypoxia-inducible factor 1alpha (HIF-1α),cyclooxygenase 2 (COX-2) and the correlation with microvessel density(MVD) in human lung cancer. Methods: HIF-1-α and COX-2 expression levels were determined by immunohistochemistry in lung cancer tissues of 48 patients. MVD was determined by immunostaining with anti-CD34 antibody. Results: HIF-1α and COX-2 were positive in 87.50%(42/48) and 77.08%(37/48),respectively,in 48 lung cancer patients. No statistical difference was found among different histopathological groups(P > 0.05). HIF-1α and COX-2 were expressed in 78.95%(15/19) and 57.89%(11/19) in early stage of lung cancer,and 93.10%(27/29) and 89.66%(26/29) in advanced stage of lung cancer. Both expressions of HIF-1 and COX-2 were positively correlated with the clinical stages of the patients(P < 0.05). In addition,the expression of HIF-1α and COX-2 were positively correlated with MVD in the lung cancer tissue(P < 0.05). The MVD of lung cancer tissue in which both HIF-1α and COX-2 were positive stained was higher than that in the group in which both HIF-1α and COX-2 or either of them was negatively expressed (P < 0.05). Conclusion: HIF-1α and COX-2 are important factors in the angiogenesis of lung cancer and may have a synergistic effect.