The safety, accuracy, reliability, noninvasiveness, and ease of use make pulse oximetry a valuable addition to oxygen monitoring of infants in special care nurseries. Such instruments are less sensitive to changes in peripheral circulation or to edema, making them more reliable in sick, physiologically unstable babies and in chronically ill babies with bronchopulmonary dysplasia. In these infants, rapid and accurate measurements of oxygen saturation with such instruments can promote optimal ventilator and oxygen management. In addition, observation of changes in oxygenation during various aspects of care can help optimize care plans for each infant. Although there remains a need for knowing PO2 in preterm infants, pulse oxygen saturation monitoring adds an important degree of control of oxygen management.