The diagnosis of brain death requires absence of respiratory effort. Various protocols for apnea testing in adults have been reported; however, similar protocols have not been established for children. The technique of apneic oxygenation was used on 10 brain-dead children, PaO2remained over 200 torr in all patients, and the mean Paco2increase was 4 torr/min. Five min of apneic oxygenation is a safe and effective means of evaluating respiratory activity in initially normocapnic children thought to be brain-dead.