Purpose: Evaluating the influence of pulmonary arterial hypertension in the treatment of congenital diaphragmatic hernias. Method: Description comparative method between 2 groups: Congenital diaphragmatic hernias neonates with pulmonary arterial hypertension and congenital diaphragmatic hernias neonates without pulmonary arterial hypertention during and post endocopic thoracic surgery. Results: Among 75patients suffering congenital diaphragmatic hernias, 38 of them had pulmonary arterial hypertension before operation. Children having both congenital diaphragmatic hernias and pulmonary arterial hypertension are 5 times more likely to have apnea than those without pulmonary arterial hypertension. Besides, neonates with both diseases are 6 times more likely to present congenital malformation than those without pulmonary arterial hypertension. 'Pulmonary arterial hypertension has no influence on patients with congential diaphragmatic hernias during surgery. After surgery, patients suffering both diseases are more likely to have respiratory failure, infections and higher mortality rate. Conclusion: Pulmonary arterial hypertension causes failure of the treatment of congential diaphragmatic hernias.