Juvenile myoclonic epilepsy: clinical features and age at onsetJuvenile myoclonic epilepsy (JME) is a syndrome with distinctive characteristics. The purpose of this study was to compare the frequencies of associated clinical features, dificulties to achieve usual life activities coming from myoclonic episodes, relapses and persistence of specific electroencephalographic abnormalities after treatment among patients with myoclonic epilepsy beg in ing before (children) and after (adolescents and adults) age 14 years. Thirty-seven children 6 to 1 3 years of age and 31 adults and adolescents aged 14 to 59 years were followed since 1981 for an average period of 24.17 months (range 1 to 83 months). All patients except one, received valproic acid. The electroencephalograms were carried out under standard conditions. Most children <64.8%) and adults (58.1%! had at least one family member with afebrile epileptic seizures. A majority of affected children 486.5%} and adults (74.2%) showed difficulties in their daily live activities. Relapses occurred in 35.1% children and 29.0% adults, mainly along the first year of treatment, and it was usually due to noncompliance. In only 7.4% children and 1 2.0% adult patients the specific alterations shown in the initial electroencephalogram persisted after treatment with valproic acid. Thus there were not significant differences between children and adult onset myoclonic epilepsy patients when compared by the above mentioned criteria.