During a 3-year period (1979-81) 85 premature infants with idiopathic respiratory distress (IRDS) were treated early with an easily applicable light-weight CPAP-system with a binasal tube and a gas jet. We used conservative criteria for ventilator treatment. The treatment proved sufficient in 18 out of 25 infants with a birth weight less than or equal to 1500 g and in 53 out of 60 infants with a birth weight greater than 1500 g. Seven infants developed pneumothorax during CPAP treatment. Seventy-four infants survived, all without bronchopulmonary dysplasia. At the age of 1.5-4.5 years the incidence of respiratory tract infections did not differ from that in a group of siblings; and the incidence of lower respiratory tract infections was low compared to previous studies. With the criteria used, early CPAP proved effective in the majority of infants with IRDS.