Respiratory distress syndrome is one of the most important causes of mortality & morbidity in preterm neonates. It produces various effects from mild respiratory distress to severe respiratory failure. Respiratory sequelae of RDS usually needs respiratory support. Continuous positive airway pressure (CPAP) is one of the most import methods of assisted ventilation given for these patients and we tried in our study to find causes of CPAP failure in preterm neonates diagnosed clinically & radiologically to have RDS.