It is purpose of this study to determine the benificial effect of treatment with methylprednisolone on the enhancement of Na⁺·K⁺-ATPase activity and the increased ATP level during the 4 hours after a 400gm-cm injury to the spinal cord of cat. These results demonstrate that high dose(30mg/kg) of methylprednisolone can benificially enhance the activity of neuronal Na⁺·K⁺-ATPase during the first 4 hour after spinal cord injury. But the enharrcement of this enzyme activity is not significantly increased with mega dose(60mg/kg) of methylprednisolone. Tissue level of ATP in the high dose-treated cat at 1 hour after trauma was significantly elevated, but those in high dose-treated cat at 4 hour and the 1 and 4 hours with mega dose-treated groups were not significantly increased. The protective effects of methylprednisolone in experimental spinal cord trauma are the enhancement of Na⁺·K⁺-ATPase, inhibition of the free-radical reaction and the lipid peroxidation, the increment of neuronal activity and ATP utilization. High dose(30mg/kg) of methylprednisolone is required in order to produce the acute effect in the early phase experimental spinal cord injury.