Valproic acid was synthesized in 1882 (Burton 1882) and was used as an organic solvent. Antiepileptic properties of valproic acid, which is structurally unrelated to other antiepileptic drugs, were discovered by chance in 1963 (Meunier et al 1963). Around this same time, carbamazepine was introduced into clinical practice as an antiepileptic drug. The first clinical trials with valproic acid were reported in 1964 (Carraz et al 1964). It was marketed in France in 1967 and released in the United States in 1978. By the late 1970s, valproic acid was marketed worldwide and had attained the status of a major antiepileptic drug. It is now approved for the prophylaxis of migraine also.