We present the case of a patient with myelodysplastic syndrome who experienced leukemia transformation and subsequently underwent transplantation of unmanipulated peripheral blood stem cells from a haploidentical sibling mismatched at 3 HLA antigens, along with a reduced-intensity regimen (fludarabine, busulfan, and anti-T-lymphocyte globulin) and tacrolimus-containing graft-versus-host disease (GVHD) prophylaxis. The patient experienced graft rejection but successfully underwent a second transplantation from the same donor with a slightly intensified conditioning regimen. Although the patient developed life-threatening cytomegalovirus (CMV) pneumonia following the second transplantation, he recovered completely from the pneumonia with intensive supportive therapy. He is still in complete remission past day 1000 in the absence of GVHD. As far as we know, this report is the first to describe a successful second transplantation that was performed for graft rejection following HLA-haploidentical nonmyeloablative stem cell transplantation. Furthermore, we emphasize that patients should be carefully monitored for CMV infection when reduced-intensity conditioning is given repeatedly over a short period.