This study was undertaken in order to define the beneficial action of methylprednisolone sodium succinate on the lactate metabolism in injuried spinal cord. The spinal cord was exposed by dorsal laminectomy from L2 to L5 under the operating microscope. A 400gm - cm injury was produced at the L2 vertebral level of the cord. The lactate content peaked at 2 ours of the injury, and remained significantly elevated for 8 hours compared to uninjuried normal cord. The changes of tissue lactate in the spinal cord following injury are consistent with marked reduction in blood flow in the injuried spinal cord tissue following blunt contusion trauma. The elevation in lactate observed at 1 hour, 2 hour and 4 hour after the injury were prevented by intravenous administration of single 30 mg/kg dose of menthylprednisolone at 30 minutes after the injury. The results suggest that the beneficial effect of the intravenous administration of a 30 mg/kg dose of methylprednisolone may improve blood flow to the injuried tissue of spinal cord.