Hematopoietic stem cell transplantation (SCT) is a potentially curative treatment for patients with hematologic malignancies,such as acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS).There has been tremendous progress in the past several decades in allogeneic SCT with better outcomes through improvements in supportive care,expansion of stem cell donor options (HLA-matched unrelated donors (MUD),haploidentical related donors,and cord blood units (CBUs)etc.),and introduction of better tolerated reduced intensity conditioning (RIC) regimens.