Thirty-seven rats were anesthetized and ventilated and had continuous monitoring of mean systemic arterial pressure (MSAP) and central venous pressure (CVP). The animals underwent a 60-g clip compression injury at T-1 for 1 minute. Fifteen minutes after injury, microspheres were used to measure cardiac output (CO) and spinal cord blood flow (SCBF). Each animal was then randomized into one of five groups. Four groups received intravenous infusions for 1 hour each of 5% albumin, autologous packed cells, low molecular weight dextran, or autologous whole blood to maintain the MSAP. The fifth group served as a control group and received an infusion of normal saline. Seventy-five minutes after injury, CO and SCBF were measured. The posttraumatic reduction in CO was significantly improved by all four treatment infusions. However, only autologous whole blood and dextran successfully reversed the posttraumatic hypotension. Dextran significantly elevated the CVP (P less than 0.01) and reduced the hematocrit (P less than 0.01). Whole blood improved SCBF in all segments of the spinal cord by nearly 100% (P less than 0.05), and dextran increased SCBF by 200% (P less than 0.01). Thus, the most marked improvements in MSAP, CO, and SCBF were produced by hypervolemia and hemodilution associated with dextran infusion. The therapeutic implications of this reversal of local and systemic changes in acute spinal cord injury are discussed.