Rats treated with the NMDA-blocker, ketamine hydrochloride 30 minutes after the induction of seizures by lithium/pilocarpine exhibited statistically smaller lateral ventricles in the left hemisphere compared to rats that had received acepromazine after the induction of these seizures. In addition, the ketamine-treated rats had more neurons and glial cells surrounding the ventricles. These results suggest a neuroprotective effect of ketamine, such that there is less atrophy surrounding the ventricles and therefore, a smaller degree of dilatation. The possibility that insidious neuronal atrophy and death associated with the ventricular enlargement encourages the marked aggression in the epileptic rats not treated by ketamine is discussed.