We studied the ability of serum glucose concentration and neurologic deficits at admission in predicting the outcome of acute cerebral ischemia in 65 patients given naloxone. Among our patients, the volume of infarction on computed tomograms and outcome were strongly related to the severity of neurologic deficits found at admission. Neither a history of diabetes nor hyperglycemia when added to the results of the initial neurologic assessment improved prediction of outcome after acute cerebral infarction.