In the same way than in other areas of neurology, the development of genetics is revolutionizing our knowledge of epilepsies. In the last years, new epilepsy syndromes of genetic basis have been defined, and in some of them, the mechanism implicated in the origin of seizures has been determined. In the next years, we hope to determinate de innermost mechanisms by which epileptogenesis occurs, and to design new more rational strategies of prevention and treatment. The epilepsy syndromes in which a genetic basis has been established are presented.