aGVHD occurs when the donor’s immune cells recognize the recipient’s body as foreign and consequently attack the body. The risk of aGVHD post-transplant increases the risk of complications, morbidity and mortality post allogeneic transplant. aGVHD presents usually anywhere between 10-100 days post-transplant. About ~40-50% of our allogeneic transplant recipients are affected by aGVHD, with the highest incidence in our matched unrelated or mismatched allogeneic stem cell transplant recipients. Patients usually present first with symptoms of generalized maculopapular rash throughout the entire body and/or upper gastrointestinal tract symptoms consisting of nausea, anorexia or both. Patients will also experience lower gastrointestinal tract symptoms such as watery diarrhea, severe abdominal pain, bloody diarrhea or an ileus. aGVHD can also affect the liver causing hyperbilirubinemia. Traditionally, prevention methods for aGVHD differ per institution. Standard of care prevention usually consists of methotrexate and a calcineurin inhibitor; while mTOR inhibitors and mycophenolate are other preventative methods. T cell depletion methods such as alemtuzumab, thymoglobulin, and post-transplant cyclophosphamide are alternative methods used for the prevention of aGVHD. New published data has expanded on the use of post-transplant cyclophosphamide. Post-transplant cyclophosphamide compared to other t cell depletion methods has produced similar overall survival rates with lower incidence of side effects. This presentation will review primary literature on post-transplant cyclophosphamide utilization to prevent aGVHD. By presenting evidence-based medicine on post-transplant cyclophosphamide, this presentation will help explain to the institution’s pharmacy team the importance of this emerging method used to prevent aGVHD.