Short term sleep-EEGs of children (23 males and 7 females) with myoclonic-astatic seizures were carried out. All of them were treated with mostly more than one antiepileptic drug. An EEG during wakefulness was recorded shortly before sleep in 23 patients, whereas 7 children fell asleep at once. Sleep was induced with 2 mg/kg body weight Protactyl syrus (promazie hydrochloride). The clinical findings correspond with known results. In the wake EEG epileptic activity was recorded in 16 out of 23 cases. In the sleep EEG epileptic discharges were seen in all patients with the exception of 2, who were free of seizures. These discharges were most frequently recorded in stage B (25 times) 20 times in stage C, 18 times in stage A und 13 times in stage D. The REM-stage was never reached. Also in respect of the total duration of the recording considerably more epileptic activity was seen in the sleep EEG (29%) than in the wake EEG (16%). In 3 cases more epileptic activity was found in the wake EEG. In the 5 patients showing no epileptic discharges in the wake EEG only little epileptic activity (2.06% of the total recording time) was seen in the sleep EEG. In sleep, single epileptic paroxysm and series of epileptic discharges with and without multiple spikes as well as continuous epileptic activity with multiple spikes were more often recorded. Likewise stretches of continuous generalized spikes were more frequently seen--in 9 patients--during sleep as opposed to 2 patients in the waking state. They represent--mostly at night--subclinical or clinical tonic seizures.