Storage of red cells in acid-citrate-dextrose (ACD) solution for more than a week has been shown to cause a reduction in red cell 2,3-diphosphoglycerate (2,3-DPG), resulting in a decrease in the half-saturation pressure (P50) of stored blood, thus increasing hemoglobin-oxygen affinity and theoretically decreasing oxygen delivery to the tissues. A method to isolate and perfuse the hindlimb in a dog has been developed and used successfully to compare the difference of oxygen release between banked and fresh ACD blood. Ten dogs were perfused using canine blood collected in standard blood transfusion bags containing ACD and stored at 4 degrees C and fresh blood collected in a similar manner but used immediately. The total oxygen release in the limb during perfusion with fresh blood was significantly greater than during perfusion with stored blood.