Respiratory failure at birth is a major cause of death and disease in newborn infants. At birth the airways must be cleared of liquid to allow the inhalation of air, but, little is known about the process of lung aeration, because it has not been possible to observe or measure it. We have developed imaging and analytical techniques to observed and measure lung aeration. We will determine ventilation procedures that promote uniform lung aeration and minimise lung injury in ventilated infants.