Injured patients stress the transfusion service with frequent demands for uncrossmatched red cells and plasma, occasional requirements for large amounts of blood products and the need for new and better blood products. Transfusion services stress trauma centers with demands for strict accountability for individual blood component units and adherence to indications in a clinical field where research has been difficult, and guidance opinion-based. New data suggest that the most severely injured patients arrive at the trauma center already coagulopathic and that these patients benefit from prompt, specific, corrective treatment. This research is clarifying trauma system requirements for new blood products and blood-product usage patterns, but the inability to obtain informed consent from severely injured patients remains an obstacle to further research.