Autism, mainly affecting social interaction and verbal and nonverbal communicative functions, is not a single disease, and can be associated with different brain disorders. This chapter focuses on epileptic syndromes or types of epilepsies in which autistic symptoms can be a predominant manifestation, and can worsen or improve in direct correlation with the activity of the epilepsy, even though they probably constitute a minority of situations in which both autism and epilepsy co-occur. The structures of the limbic system thought to be involved in autistic spectrum disorders (ASD) are highly epileptogenic and are the origin of frequently encountered early childhood epilepsies or epileptic syndromes. There are numerous paroxysmal nonepileptic neurological disorders which can be erroneously diagnosed as epilepsy. The clinical diagnosis and management of autistic children and adults, while sharing the same principles as those followed with other handicapped persons, have unique features related to the specific symptoms of ASD.