Summary:Twenty-five patients with partial cognitive seizures (i.e., seizures characterized by experiential phenomena) were found in a sample of 4,000 epileptics. Seventeen of the 25 had a structural lesion shown by CT scan, and in 16 the lesion was located in the temporal lobe. No differences were found with regard to laterality of focus. The relationship of this type of seizure with some psychotic phenomena is described, and it is proposed that these seizures are a particular type of organic psychosis, and might be termed “paroxysmal psychosis.”