Angelman's syndrome is a rare genetic disorder characterized by developmental delay, craniofacial abnormalities, ataxia, paroxysmal laughter, and seizures. The diagnosis is suspected in infants who have the characteristic clinical features and electroencephalographic (EEG) abnormalities and is confirmed by the genetic identification of a maternally derived 15q11-13 deletion. We report on 3 patients with genetically confirmed Angelman's syndrome who had the characteristic clinical and EEG features. The EEGs demonstrated high-amplitude 2- to 3-Hz delta activity, with intermittent spike-and-slow-wave discharges maximal in the occipital region in 2 patients and generalized sharp-and-slow-wave discharges, occipital spikes, and electrographic status epilepticus during slow-wave sleep in the other patient. The findings of generalized high-amplitude delta slowing and occipital spike-and-wave discharges, facilitated by eye closure, in children with developmental delay and seizures suggest the diagnosis of Angelman's syndrome and should lead to genetic testing.