The epileptic encephalopathies of infancy and childhood include West syndrome, Lennox-Gastaut syndrome, severe myoclonic epilepsy of early childhood and related syndromes. The exact limits of these syndromes are still a subject of debate. The clinical features include several types of brief, frequently repeated seizures associated with mental retardation. The causes are multiple and brain malformations and dysplasias play an important role. Treatment remains unsatisfactory and the place of surgery seems limited.