Regional glucose utilization was measured in the rat brain after occlusion of the middle cerebral artery. Normoglycaemic rat had increased glucose use in the cerebral cortex adjacent to the infarct. A fraction of the nerve cells were irreversibly injured in this region. In hyperglycaemic rats, the glucose metabolism remained normal and no nerve cell loss was found around the infarct. The findings indicate that hyperglycaemia protects against nerve cell injury in the areas next to experimental brain infarcts.