Persons who suffer traumatic injury are likely to be transfused with considerable amounts of blood during initial resuscitation efforts. Oxygen-carrying solutions are currently in clinical testing as substitutes for red blood cells. Although these agents may eliminate many concerns associated with blood administration (short shelf life, infectious and immunologic risks, the need to type and cross-match), early cell-free hemoglobin solutions demonstrated nephrotoxicity and were associated with pulmonary and systemic hypertension, among other adverse events. Newer polymerized hemoglobin solutions show acceptable safety profiles in the surgical setting and studies are being designed, some with funding from the US Department of Defense, to evaluate their efficacy in hemorrhaging trauma victims.