Two reflex mechanisms important for survival are discussed. Brainstem and cardiovascular mechanisms that are responsible for recovery from severe hypoxia (autoresuscitation) are important for survival in acutely hypoxic infants and adults. Failure of this mechanism may be important in Sudden Infant Death Syndrome, since brainstem mediated hypoxic gasping is essential for successful autoresuscitation and since SIDS infants appear to attempt to autoresuscitate just prior to death. The major function of another mechanism is to protect the airway from fluid aspiration. The various components of the laryngeal chemoreflex (LCR) change during maturation. The LCR is an important cause of prolonged apneic spells in infants. Consequently it also may have a role in causing SIDS. Maturational changes and/or inadequacy of this reflex may be responsible for pulmonary aspiration and infectious pneumonia in both children and adults.