Aim To investigate the influence of granulocyte-macrophage colony stimulating factor on functional activity of rat endothelial progenitor cells in vitro in order to further provide experimental basis for the mechanism of reendothelialization and prevention and treatment of coronary artery disease.Methods Endothelial progenitor cells were separated from bone marrow and spleen of rat with density gradient centrifugation method.Then growth and differentiation procession of endothelial progenitor cells were observed with inverted phase contrast microscope.Endothelial progenitor cells were identified via dual fluorescent staining of FITC-AC133 and PE-vWF.After cultured for seven days,endothelial progenitor cells were added stimulating factors.Then the influence of granulocyte-macrophage colony stimulating factor on proliferation,transfer and blood vessels formation of endothelial progenitor cells were detected with MTT colorimetry,Transwell chamber and Matrigel.Finally the experiment results were analysed.Results Compared with control,granulocyte-macrophage colony stimulating factor significantly increased OD490,the number of migratory cells and tubes(P<0.001).Conclusions Granulocyte-macrophage colony stimulating factor can significantly facilitate proliferation,migration and blood vessels formation of endothelial progenitor cells in vitro.