Aim To establish a method for tracking bone marrow mesenchymal stem cells(MSC) through transfection of enhanced green fluorescence protein(EGFP) gene.Methods Mesenchymal stem cells were isolated from bone marrow and purified by density centrifuge in vitro.The cultured cells were transferred with the expressing plamid of EGFP(pEGFP) by means of lipofectamine media methods.The transient expression and transfection efficiency were subsequently observed by fluorescent microscopy.Results The expression of EGFP was initially found in 12 h after transfection,reached optimal state in 48～72 h,remained strong express within 1 week and than became weak for 4 weeks.The efficiency of transfection was correlated with the concentration of plamid and lipofectamine respectively.Particularly,the growth and proliferation of mesenchymal stem cells wasn't disturbed by EGFP gene transfection.Conclusions EGFP transfected by lipofectamine media could be safely expressed in MSC in vitro.The efficiency of transfection could reach 20%～30% with proper concentration of plamid and lipofactamine.EGFP as a report gene to label stem cells was an ideal method for tracking.