 Over the last two decades, it has been recognized that the relatively increasing incidence of bleeding and thrombotic complications correlating to the prognosis and quality of life for HSCT recipients. Previous studies have shown that conventional risk factors including graft-versus-host disease GVHD, infection, thrombocytopenia, the anticoagulation therapy, damage of endothelial cell and conditioning regimen can contribute to the onset of hemostatic disorders in HSCT recipients or can even exacerbate the process. Nevertheless, their roles and detailed pathogenesis in the development of bleeding and thrombosis remain undefined and limited data in Asian population was known about the competing risks of thrombosis and bleeding. 