Objective To observe the effect of vascular endothelial growth factor(VEGF) on endothelial progenitor cells(EPCs) and to elucidate its possible mechanism.Methods Mononuclear cells(MNCs) isolated from bone marrow by density gradient centrifugation combined with adherent cell filtration were plated on fibronectin-coated culture dishes.After culturing for 7d,adherent cells were cultured with different concentrations of VEGF(25,50,75,100 μg/L) for 48 h.EPCs proliferation and migration ability were observed and adhesion assay was performed.The endothelial nitric oxide synthase(eNOS) mRNA expression of EPCs was measured by RT-PCR.Results VEGF dose-dependently increased the number of EPCs and promoted EPCs proliferation,migration and adhesive capacity.VEGF could upregulate eNOS mRNA expression of EPCs.Conclusion VEGF might affect the biological functions of EPCs through upregulation of eNOS mRNA expression of EPCs.