To analyze the outcome of allogeneic peripheral blood stem cell transplantation(allo PBSCT) for hematological malignancies and prevention of complications, forty one patients with hematological malignancies were treated with allo PBSCT. One regimen of prophylaxis for acute graft versus host disease(GVHD) was the combination of cyclosporine(CsA)and methotrexate(MTX),another mycophenolate mofetil(MMF) with cyclosporine and methotrexate .The results showed that all patients were successfully engrafted .The incidence of over grade Ⅱ acute GVHD after HLA matched transplantation was 21 05%(8/38). Chronic GVHD occurred in 19/25(76%) patients. Three of thirty four patients with acute leukemia(CR 1 ) and CML(CP) after HLA matched transplantation relapsed(8 82%). The disease free survival was 71 43%(10/14) after follow up for more than 2 years. The results suggest that the incidence of acute GVHD in allo PBSCT appears to be similar to allo BMT, but the incidence of chronic GVHD in allo PBSCT is higher than that in allo BMT. Infection and interstitial pneumonitis are the main cause of death.