Abstract: Objective:To investigate the expressions of Delta-like ligand 4(DLL4) and vascular endothelial growth factor(VEGF) in non-small cell lung cancer(NSCLC) and normal lung specimens taken from non-cancerous regions adjacent to lung cancer tissue and analyze their correlation with clinical pathological factors as well as explore the role of them in the occurrence and development of NSCLC.Methods:The expressions of DLL4 and VEGF in 73 cases of NSCLC tissue and 32 cases of normal lung specimens taken from non-cancerous regions adjacent to lung cancer tissue were examined by EliVision immunohistochemistry method.Results:The positive rate of DLL4 and VEGF in NSCLC were significantly higher than those in adjacent normal lung tissue.In NSCLC tissues,the expressions of DLL4 and VEGF were closely related to TNM stage,lymph node metastasis(except DLL4) and histological grade(P0.05 to P0.01),but not to gender,age and histological type(P0.05).A positive correlation was observed between the expressions of DLL4 and VEGF(P0.05).Conclusions:The positive correlation between high-expressions of DLL4 and VEGF suggested that they might co-participate in the invasion/metastasis and prognosis of NSCLC through interacting with each other.DLL4 and VEGF may serve as a new therapeutic target of NSCLC patients.