To investigate effects of recombinant human erythropoietin (rhEPO) plus recombinant human granulocyte colony stimulating factor (rhG-CSF) on mobilization of CD90 + CD34 − and Sca-1 + stem cells in mice. rhEPO 1000 IU·kg −1 ·d −1 per mice alone or plus rhG-CSF 250 μ g·kg −1 ·d-1 −1 per mice was administered to mice for five days, the peripheral blood was collected at 6 hours, 1, 3,5 and 7 days after the last administration. The number of white blood cells (WBC) and mononuclear cells (MNC) was counted. The level of CD34, CD90 and Sca-1 mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR).The expressions of CD90 + CD34 − in absolute nuclear cells of peripheral blood was detected by flow cytometry. The results indicate that compared to mobilizing by rhG-CSF, rhEPO or plus rhG-CSF did not significantly enhance the number of WBC and MNC, on the fifth and the seventh day after the last administration, both the expression of CD34,CD90 and Sca-1 mRNA and the proportion of CD90 + CD34 − cells dramatically raised in rhEPO or in addition to rhG-CSF groups. We conclude that rhEPO or plus rhG-CSF had a strong capacity of mobilization of stem cells. The alteration of expression of CD34, CD90 and Sca-1 mRNA after the administration of rhEPO or combined with rhG-CSF indicated that this agents might potentially alter the peripheral blood graft content.