Abstract: Objective:To investigate the alteration of donor's lymphocyte subpopulation and haemopoietic stem cell before and after rhG-CSF mobilization in allogenic peripheral blood stem cell transplantation.Methods:Before and after recombinant human Granulocyte-Colony Stimulating Factor（rhG-CSF） mobilization,lymphocytes and CD34⁺ cells were stained directly and counted by flow cytometry.Stem cell clone proliferation was estimated by CFU-GM with methylcellulose semisolid medium.Results:Before rhG-CSF mobilization,the percentage of CD34⁺ cells was 0.12±0.08 and CFU-GM was 12±6.After rhG-CSF mobilization the percentage of CD34⁺ cells increased to 0.83±0.26 and CFU-GM increased to 102±16.Tymphocyte subpopulation didn’t change significantly after rhG-CSF mobilization.Conclusion:After rhG-CSF mobilization,the percentage of donor's CD34⁺ cells increases greatly and lymphocyte subpopulation doesn't change significantly.