The effect of continuous positive airway pressure (C.P.A.P.) on the breathing pattern of ten newborn infants with respiratory-distress syndrome (R.D.S.) has been studied using an impedance pneumograph; arterial oxygenation improved and respiration, previously disorganized, became regular in both rate and depth. Grunting usually ceased within 15 minutes of the start of C.P.A.P., and there was also on average a 30 percent increase in the respiratory-rate. The rapidity with which the breathing pattern changed suggests a reflex mechanism. Sudden reductions in airway pressure were frequently followed by apnoea, regular breathing restarting with the reintroduction of C.P.A.P. These observations suggest that C.P.P.A. provides a respiratory drive in babies with R.D.S., possibly mediated through the Hering-Breuer inflation reflex.