Summary:The development of new antiepileptic drugs is poised on the cusp between empiricism and the rational scientific development of medicaments designed to perform specific neurophysiologic functions in keeping with modern ideas of epilepsy generation and spread. It takes into account the difference between seizures and their underlying disorder known as epilepsies and the fact that, although seizures can be effectively treated with pharmacologic agents, the development of epilepsy requires both a predisposition (which may be innate or preventable) and precipitating factors that determine the timing of the individual seizures. The local membrane phenomena or cellular substrates of epilepsy can be described, as can the process of epileptogenesis. New antiepileptic development can be viewed in the light of these concepts.