Plerixafor (Mozobil®) is a CXCR4 antagonist that rapidly mobilizes CD34+ cells into circulation. Recently, plerixafor has been used as a single agent to mobilize peripheral blood stem cells (PBSC) for allogeneic hematopoietic cell transplantation. Although G-CSF mobilization is known to alter the phenotype and cytokine polarization of transplanted T-cells, the effects of plerixafor mobilization on T-cells have not been well characterized. In this study, we show that alterations in the T-cell phenotype and cytokine gene expression profiles characteristic of G-CSF mobilization do not occur following mobilization with plerixafor. Compared to non-mobilized T-cells, plerixafor-mobilized T-cells had similar phenotype, mixed lymphocyte reactivity, FoxP3 gene expression levels in CD4+ T-cells, and did not undergo a change in expression levels of 84 genes associated with Th1/Th2/Th3 pathways. In contrast to plerixafor, G-CSF mobilization decreased CD62L expression on both CD4 and CD8+ T-cells and altered expression levels of 16 cytokine-associated genes in CD3+ T-cells. To assess the clinical relevance of these findings, we explored a murine model of GVHD in which transplant recipients received plerixafor or G-CSF mobilized allograft from MHC-matched, minor histocompatibility mismatched donors; recipients of plerixafor mobilized PBSC had a significantly higher incidence of skin GVHD compared to mice receiving G-CSF mobilized transplants (100% vs. 50% respectively, p=0.02). These preclinical data show plerixafor, in contrast to G-CSF, does not alter the phenotype and cytokine polarization of T-cells, which raises the possibility that T-cell mediated immune sequelae of allogeneic transplantation in humans may differ when donor allografts are mobilized with plerixafor compared to G-CSF.