A neurochemical basis for many of the epilepsies has long been suspected to result from an imbalance between the various neurotransmitter mechanisms. The present study was undertaken to gain an understanding of the brain neurotransmitter involvement in experimental epilepsy. Adult male Holtzman strain rats were subjected to convulsions triggered by intracortical (somatosensory cortex) penicillin (PCN) administration (100 IU, 100 μl) and the regional brain levels of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) were assayed in epileptic rats. The results of the study revealed a decrease in the NE level in the cerebral cortex (cc), cerebellum (cb), caudate nuclei (cn) and midbrain (mb) except an increment in the chronic cortical NE. On the other hand DA level had increased significantly in the cc and mb though in the cb and cn the level had lowered. 5-HT levels were decreased in the cb, cn and mb while in the cc an enhanced level of 5-HT was observed. The results obtained clearly show that the nervous structures tested with PCN had a different neurotransmitter response pattern which significantly changed along the cortico-cerebellar axis.