The administration of allogeneic red blood cell transfusions to the trauma patient is an essential and potentially life-saving component of trauma care. The big question is when to transfuse, and how much? In this review, we explore the evidence and provide rationales for current and future red blood cell transfusion strategies in the trauma patient. We also discuss the changing trends and competing risks associated with transfusions as well as current evidence for different blood conservation strategies in the context of trauma.