Objectives　To investigate the efficacy of accelerating hemopoietic reconstraction and reducing a graft versus host disease (GVHD) in Allo-BMT receiving lenograstim stimulated donor marrow and to assess the preliminary biological mechanism . Methods　The donors for thirty patients (study group) with leukemia were given lenograstim 3-4?μg*kg-1*d-1 for seven days prior to marrow harvest. The results of subsequent engraftment in the recipients was compared with fifteen donors without G-CSF (control group). Five donors themselves were studied to assess the effects of lenograstion on hematopoietic progenitor cells and lymphocyte subsets in BM. Results　The stimulated bone marrow contained a higher number of nucleated cells, CFU-GM and CD34+ cells (P<0.01). The hematopoetic reconstitution was accelerated. Until granulocyte counts exceeded 0.5×109/L and plalete counts exceeded 20×109/L, the days were 16.7±3.2 and 18.4±3.0 days as compared with those of the control group (22.5±5.1 and 26.3±5.9 days respectively, P<0.01). The incidence of grade Ⅱ-Ⅳ aGVHD was very low, only one case with grade Ⅱ aGVHD on the skin in the study group. Four out of fifteen patients (26.7%) in the control group had grade Ⅱ-Ⅳ aGVHD (P<0.05). The number of T lymphocyte subsets in the harvested BM stimulated by G-CSF changed. In comparison with the control group, CD4+ decreased and CD8+ increased significantly (P<0.01). The changes of progenitor cells and T lymphocyte subsets in BM from pre- to post- G-CSF stimulation indicated that the percentage of CD4+ cells reduced (P<0.05), that of CD8+ cells, and that of CD34+ increased (P<0.01). The incidence of chronic GVHD and relapse of leukemia were not different significantly between both groups. Conclusions　Allogenic bone marrow transplant (Allo-BMT) donors given G-CSF can accelerate engraftment and minimize the incidence of severe aGVHD. There is a trend in favour of improved transplant-related complicatians.