In this study of unrelated-donor transplantation for hematologic cancers, survival was similar with bone marrow and peripheral-blood stem-cell grafts. However, graft failure was more common with the former, and chronic graft-versus-host disease with the latter. In the early days of allogeneic hematopoietic stem-cell transplantation, the only graft source available was bone marrow harvested from the pelvis of a donor under anesthesia. When studies showed that an increased dose of bone marrow cells correlated with more robust hematopoietic engraftment and lower mortality from infectious complications, transplantation centers began to use filgrastim-stimulated peripheral blood, which has a much higher content of blood progenitor cells than bone marrow, although there was concern that the higher T-cell content might increase the risk of graft-versus-host disease (GVHD). 1 – 5 Several large, randomized trials of transplantation between HLA-identical siblings showed that peripheral-blood . . .