Recent progress in hematopoietic cell transplantation has been associated with the development of stem cell sources such as peripheral blood or cord blood, alternative donors, novel strategies of immunosuppression, and reduced intensity conditioning (RIC) regimens. Many recipients often experience various complications, so identification of risk factors for these complications may help to further improve transplant outcomes. The impact of conditioning intensity on HCT outcomes has remained a matter of debate. This study was done to study the impact of intensity of the conditioning regimens on clinical outcome of patients who underwent allogenic hematopoietic stem cells transplant regarding, rate complications & early post-transplant mortality. This was an observational model single center study, and it was retrospective registry-based analysis. This study included adult Egyptian patients who underwent Allo-HSCT at Nasser institute from the reference year of 2012 through 2022. This study included adult patients ≥ 18 years of age, with allogeneic stem cell transplantation, with matched sibling donor, planned to have Myeloablative conditioning (MAC) or non-myeloablative conditioning/Reduced intensity conditioning (NMA/RIC) Allo-HSCT. The results showed that the conditioning intensity MAC vs. NMA/RIC had no significant impact on post-transplant complications. No significant impact on overall survival, MAC was associated with a trend towards lower incidence of non-relapse mortality (NRM)., we concluded that the conditioning intensity (MAC vs. NMA/RIC) Had no significant impact on post-transplant complications, although MAC is associated with longer time to hematopoietic recovery. No significant impact on overall survival, MAC was associated with a trend towards lower incidence of NRM