Abstract : GvHD is the main cause of allogeneic stem cell transplant related mortality in both pediatric and adults. GvHD occurs when donor’s T cells do not show tolerance against specific proteins on host cells. There are several methods for prevention and control of GVHD, including corticosteroids (especially prednisolone) as the first line therapeutic approach. But drug resistance to immunosuppressive drugs in some patients on one hand, and infection due to overuse of them on the other hand, has failed this treatment in 30-40% of transplanted patients. It is now believed that substituting preventive methods for GVHD rather than treating it is more reliable. Mesenchymal Stem Cell (MSC) Therapy as a new therapeutic approach has been used for reducing the risk of GvHD. Hematopoietic stem cells (HSCs) were proposed in some previous researches as positive tools in reducing the risk of GvHD. During this study, we first isolated and prepared MSCs and HSCs. The levels of sDNAM1 as a predictor biomarker of GvHD as well as blood levels of ST2, TNFR1, REG3α and sDNAM1 and Treg cell biomarkers of allogeneic transplant patients were evaluated before and after co-transplantation of HSCs and MSCs. According to this study, the co-transplantation of HSCs and MSCs did not show a significant difference compared to the group received MSCs alone