Benign myoclonic epilepsy of infancy (BMEI) is an idiopathic disorder characterized by spontaneous myoclonic attacks with onset in the first 2 years of life. We observed 6 neurologically normal infants (aged 6-21 months) with attacks that resembled those of BMEI but that occurred as reflex responses to unexpected auditory and tactile stimuli. four infants also had rare spontaneous attacks. These reflex attacks consisted of isolated muscle jerks or clusters of up to eight symmetric limb jerks affecting mainly the arms. Five of the children had a family history of epilepsy or febrile convulsions. Myoclonic attacks disappeared in 4-14 months. In 3 patients, the jerks stopped spontaneously; the others responded to valproate (VPA). Myoclonus could be elicited in wakefulness and in sleep. Ictal EEGs showed brief generalized spike- or polyspike-and-wave discharges. Interictal EEGs were normal during wakefulness; during sleep, brief generalized discharges were evident. We propose that reflex myoclonic epilepsy of infancy (RMEI) is a new age-dependent idiopathic generalized epileptic (IGE) syndrome, with an apparently good prognosis.