Abstract: Objective To investigate the effects of Dangshen (DS)on proliferation of mesenchymal stem cells (MSCs).Methods DS solution was distilled and precipitated in ethanol MSCs were separated from adult human bone marrow with Ficoll-Paque reagent and expanded in culture medium.P5-P10 cells were treated with DS (DS group) or without DS(control group).After 3 days,effects of DS on cellm orphology,proliferation and immunophenotypes were analyzed with a phase microscope,MTT colorinetric assays and flow cytometry,respectively.Results Compared with the control group(0.440±0.066,0.822±0.097),them etabolic activities of cells treated with DS (0.535±0.041,0.972±0.129) increased significantly(P<0.05).The percentage of S phase in DS group(2.14±0.25)was higher than that of in control group(1.10±0.04,P<0.05) and the percentage of apoptotic cells in DS group(1.04±0.620)was lower than that of in control group (3.45±1.33%,P<0.05).Cells treated with DS were unifounly positive for CD105,CD166,negative for CD34,CD45 and changes in morphology were not observed.Conclusion DS can promote the proliferation of MSCs and keep the MSCs in the undifferentiated state.