In newborns and infants a variety of respiratory disorders lead to ventilatory failure. In early life the ventilatory response to loaded breathing is limited. The risk factors of ventilatory failure are related to the developing respiratory pump because of the immaturity of the chest wall, respiratory muscles and coupling between thoracic and abdominal movements. Assessment of respiratory muscle function in infants is limited, due to the objections to using invasive techniques. However, measurement of airway pressures during crying may provide an index of respiratory muscle strength in infants. Real-time ultrasonography allows investigation of diaphragmatic movements. Pattern of thoracoabdominal motion can be assessed using uncalibrated respiratory inductive plethysmography. Finally, electromyographic recording of respiratory muscles by surface electrodes is of clinical usefulness during sleep studies.