 In Canada, over 1,500 autologous hematopoietic stem cell transplantations ASCT are performed annually for hematologic malignancies. It is currently standard practice to provide a prophylactic transfusion of platelets to prevent bleeding when the daily measured platelet count is less than 10 x 109L. A patient may require up to six adult platelet doses during the post-transplant period. However, the true benefit of prophylactic platelet transfusions in the ASCT setting is unclear and has been called into question by several recent studies. 