Introduction. More new antiepileptic drugs (AED) have been introduced over the last decade than in the past 40 years -a fact that has improved our therapeutic capabilities, especially in the case of refractory epilepsies. Development. The new AED, generally speaking, have a longer half-life, lower rate of protein attachment and a fewer side affects, and interaction takes place to a lesser extent either with other AED and drugs. Yet, paediatric formulations are few, costs are high in developing countries and in such countries their use is often limited by the fact that they are simply not available. Conclusions. The new AED offer a number of advantages over the classical agents as far as pharmacokinetics and metabolism are concerned, since they do not interact with other medications so frequently. Despite the high economic cost for developing countries, the general impression is that they do indeed reduce the social cost. © 2006, Revista de Neurología.