Material and methods: Prespective study, description of serial cases was performed on 30 preterm infants diagnosed of respiratory distress syndrome, gestational age from 24 to 35 weeks, postnatal age < 24 hours, bithweight from 900 to 2250 gram, no indication for mechanical ventilation and no congenital malformation. They were admitted to the Neonatology department in Tu Du Hospital from 09/2008 to 08/2009 and were treated with surfactant replacement by using insure method.