This study aimed to evaluate the efficacy of reduced intensity conditioning (RIC) regimen in low- and intermediate-risk myelodysplastic syndrome (MDS) patients who receive haploidentical hematopoietic stem cell transplantation (haplo-HSCT). Haplo-HSCT is an effective treatment option for MDS patients who did not have identical sibling donor (ISD) or unrelated donor (URD). However, post-transplant transplant-related mortality (TRM) is one of the major causes for transplant failure in MDS patients, and the risk of TRM for haplo-HSCT recipients was higher than that of ISD recipients. RIC regimen can decrease the risk of TRM for haplo-HSCT recipients; however, the risk for relapse may increase in these patients. Thus, RIC regimen may be more appropriate for low- and intermediate-risk MDS patients receiving haplo-HSCT. The study hypothesis: Using RIC haplo-HSCT regimen in patients with low- and risk MDS can reduce TRM and improve survival.