Utilization of nitric oxide (NO) therapy has been related to a trend towards short term improvement in very premature infants. A two year follow-up of children treated soon after birth with NO in the neonatal period, suggests that a significant improvement in neurodevelopmental outcome might occur. This study aims to evaluate follow-up at 6 years, in respiratory and neurodevelopmental outcome, of children born very prematurely, some of them having been treated with nitric oxide in the neonatal period.