Recombinant human granulocyte colony-stimulating factor (rhG-CSF)-mobilized peripheral blood stem cells (PBSC) are now widely used for autologous transplantation to provide hematopoietic stem cells after intensive chemoradiotherapy. However, PBSC which contain a large number of T cells represent a potential risk for graft-versus-host disease (GVHD) in allogeneic (allo) transplantation. There are about 50 case reports of clinical trials of rhG-CSF-mobilized allo PBSC transplantation (PBSCT) with relatively rapid hematological recovery, without severe acute GVHD except in a few cases. Therefore, the risk of inducing severe acute GVHD is not as high as was expected when allo PBSCT began. However, whether allo PBSCT will increase the risk of chronic GVHD is not clear, because the period of observation has been too short. Also, it will be of interest to determine the clinical effect of allo PBSCT on relapse of hematological malignancy post-transplant. Whether allo PBSCT will increase life-threatening acute and chronic GVHD, and whether PBSC allografting will result in permanent hematological and immunological reconstitution has to be determined by prospective randomized clinical trials.