In order to determine the impact of extremely large doses of methylprednisolone, naloxone, or of spinal cord injury itself, on liver enzymes, we examined the results of SGOT, SGPT, alkaline phosphatase and total bilirubin tests obtained 24 hours, 3 and 10 days after the end of the study drug infusions in spinal cord injured patients entered in the National Acute Spinal Cord Injury Study. The mean values of four liver enzymes, the amount of change between 24 hours and 3 and 10 days post infusion, and the proportion of liver enzyme levels considered to be abnormal did not appear to be affected by either drug protocol. Even when controlling for drug protocol and severity of injury (complete vs incomplete), variation in enzyme levels appeared to be the result of the spinal cord injury, not study drugs. Spinal cord injury is routinely treated with the NASCIS dose of methylprednisolone in many countries. It is reassuring to find no evidence of compromised liver function from this steroid protocol.