The hypothesis that acid gastroesophageal reflux may be responsible for the persistence of apnea was tested on 20 prematurely born infants, at a median conceptional age of 38.7 weeks. Gastroesophageal reflux was identified using distal esophageal pH monitoring. Apneas of durations greater than 10 seconds were identified and classified as either central or obstructive and mixed, using recordings of respiration. Wakefulness, active sleep, and quiet sleep were identified using electroencephalography and by assessing eye movements. Of 134 episodes of acid gastroesophageal reflux in the 20 subjects, more occurred during wakefulness and during active sleep than during quiet sleep. A total of 139 apneas, predominantly of the obstructive and mixed type, occurred. No relationship could, however, be demonstrated, in this rather small number of patients, between the occurrence of gastroesophageal reflux and that of apneas.