Hyperglycemic rats were exposed to 10 min of complete cerebral ischemia. Rats with 26 mM (range 23-27 mM) plasma glucose levels died. Rats with the same degree of hyperglycemia, treated after ischemia with pentobarbital (75-95 mg/kg) or diazepam (10-13 mg/kg), survived the observation period of 21 days and recovered, albeit incompletely. The same treatment given to rats with higher degrees of hyperglycemia did not prevent death. It is concluded that postischemic treatment with anticonvulsive drugs may improve clinical restitution from ischemia in moderately hyperglycemic rats.