A light-weight system for continuous positive airway pressure (CPAP) based on a nasal vestibular cannula and a miniature gas jet has been tried out in 29 newborns with severe idiopathic respiratory distress syndrome (IRDS) and nine infants suffering from respiratory insufficiency caused by lower respiratory tract infections. In infants with IRDS, a permanent effect was achieved in 20% when the birth weight was below 1501 g, and in 74% when the birth weight was higher. The infants with lower respiratory tract infections all recovered without further ventilatory support. Significant complications occurred in only two infants, both of whom developed pneumothorax. The system forms a simple and safe alternative to existing nasal CPAP systems suitable for use in newborns as well as older infants with lung diseases resulting in alveolar collapse.