We report video-EEG findings and a long-term follow-up study in 10 patients with benign myoclonic epilepsy in infants (BMEI). A high incidence of a past and family history of febrile convulsions was noted. Six of the 10 patients manifested characteristic vocalization associated with myoclonic seizures. It consisted of a sudden, brief expiratory noise and is considered to be characteristic of BMEI. Afebrile convulsions occurred before the onset of myoclonic seizures or during the clinical course in six patients, but the accurate type of these seizures remains to be clarified. Monotherapy with valproatic acid (VPA) was very effective, but plasma VPA levels over 100 micrograms/ml were initially necessary in most of the cases, although they did not need to be maintained for further seizure control. All patients showed a favorable long-term seizure outcome, although one showed moderate mental retardation.