The occurrence of post-infarction epilepsy was investigated in 68 patients with angiographically proven internal carotid artery occlusion and in 56 patients with middle cerebral artery occlusion. Epileptic seizures occurred during follow-up in 9% of the carotid artery group and in 21.4% of the middle cerebral artery group. The different incidence of seizures in the two groups was statistically significant. The physiopathological mechanism of the late post-infarction epilepsy is discussed.