Objective:To investigate the effects of icaritin(ICT)on the proliferation and osteogenic differentiation of rat bone mar-row stromal cells(rBMSCs).Methods:rBMSCs were cultured from the bone marrow of SD rats and identified by multilineage differ-entiation assays.3,6 and 9 days after the treatment of rBMSCs of passage 4 by ICT at 1 0 -9 ,1 0 -8 ,1 0 -7 ,1 0 -6 and 1 0 -5 mol/L re-spectively,the proliferation and differentiation of the cells were examined by cck-8 and alkaline phosphatase (ALP)activity assay kit respectively.The calcium nodule formation was observed by alizarin red(AR)staining 21 days after 1 0 -9 mol/L ICT treatment. Results:Primary rBMSCs showed the typical spindle-like shape with attachment growth.rBMSCs could be induced to osteogenic and adipogenic differentiation.The proliferation of rBMSCs was inhibited but ALP activity was enhanced by ICT.1 0 -9 mol/L ICT in-cresed calcium nodule formation.Conclusion:ICT can dose-dependently inhibit the proliferation,but promote the osteogenic differ-entiation of rBMSCs.