Disruption of the periodic pattern in the EEG was observed in a patient with Jakob-Creutzfeldt disease. Periods of apnea (during 'sleep') were associated with abrupt cessation of the periodic complexes and their replacement by 7-9 c/sec waves which persisted throughout the apneic episode. The periodic complexes reappeared on termination of the apnea. This close temporal association between disruption of the periodicity and apneic episodes suggests proximity of respiratory neurons and the deep subcortical pacemaker.