Hypoxia caused by pneumonia or bronchiolitis is a common cause of death in children in developing countries. Oxygen is very expensive in developing countries, and it is important that the limited supplies available be used as efficiently as possible. This study evaluated the administration of oxygen through an 8 FG catheter inserted into the nose to a depth equal to the distance from the side of the nose to the front of the ear, so that the tip of the catheter was just visible in the pharynx below the soft palate. A flow rate of 150 ml/kg/min gave an inspired oxygen concentration of about 50% in children less than 2 years old. Thus, newborn infants with pneumonia can usually be treated with 0.5 l/min and infants up to 12 months old with 1.0 l/min of nasopharyngeal oxygen.