Objiective To explore feasibility and efficacy of unrelated donor peripheral blood stem cell transplantation (UD-PBSCT) in treatment of hematologic malignancies.Methods Thirty patients with hematologic malignancies undewent high resolution DNA based typing HLA-matched or 1 locus mismatched UD-PBSCT from Oct.2002 to Dec.2006.Busulfan,cyclophosphamide,Ara-C,MeCCNU and antithymocyte globulin (ATG) were used for preparative regimen in 25 cases,while TBI,cyclophosphamide and ATG were used in 2 cases,and fludarabine,busulfan and ATG was used in one case.All patients received mycophenolate mofetile,cyclosporin A and short-term methotrexate with or without CD25 antibody as the graft-versus-host disease (GVHD) prophylaxis.Results The results showed that rapid engraftment was observed in all cases who presented full donor chimerism at 28 days post transplantation by STR-PCR.The median time of neutrophil recovery＞0.5×109/L,platelet recovery＞20×109/L was observed at 15,16 days respectively post transplantation.The incidence of acute GVHD was 20％(6/30 cases,3 cases with grade Ⅰ,2 cases with grade Ⅲ,1case with grade Ⅵ).The incidence of chronic GVHD was 33％.Disease free survival of 3 years is 78％ in good prognostic group.Conclusion It is concluded that above-mentioned conditioning and GVHD prophylaxis are effective approaches for unrelated donor peripheral blood stem cell transplantation in treatment of hematopoietic malignancies.