G-SCF-mobilized PBSC (GPB) grafts have a higher cell dose and somewhat more committed progenitor cells than steady-state BM (SBM), resulting in faster engraftment and faster immunological reconstitution. On the other hand, transplant related mortality (TRM), disease-free survival (DFS) and overall survival (OS) are similar both for PB and for BM. In contrast to SBM, G-CSF-primed BM (GBM) grafts stimulate HSC proliferation, increasing cell dose and thus resulting in faster engraftment because of higher cell dose infused, or because of treatment with G-CSF. Furthermore, GBM may induce tolerance and functional modulations in donor hematopoiesis and immunity, further reducing GVHD incidence, which is already lower with SBM compared with GPB grafts. Overall, a growing body of clinical evidence suggests that GBM transplants may share the advantages of GPB transplantations, without the associated increased risk of GVHD, and might be an attractive graft source for allogeneic SCTs.