Objective: By studying newborn with persistent pulmonary hypertension retrospectively at OUS Rikshospitalet (the national referral facility), it may add some knowledge about this serious neonatal respiratory disease. Material and methods: All neonates born with PPHN and admitted to NICU at the national referral hospital (n=164) in Norway during 2002-2011 were included in the study. Of these, 107 neonates were transported from their local hospital to Rikshospitalet, while 57 neonates were delivered at the referral facility. Median GA was 39.2W, median birth weight 3410 g. 61, 6% were boys and 38, 4% girls. Apgar score, associated conditions and diagnosis after echocardiography were recorded. Duration of treatments like oxygen, inhaled nitric oxide, assisted ventilation, sedation, vasopressor support and extracorporeal membrane oxygenation were also noted. This parameters were used to evaluate the characteristics and severity of PPHN. We could also calculate the incidence of this disease in Asker and Bærum municipality in Norway. Results: The incidence of PPHN is estimated to 1,0 per 1000 live births. In neonates with PPHN, the median Apgar score after 1 minute was 7 and after 5 minutes 8. 92,1% needed oxygen and the median of this treatment was 7 days. Median of CPAP was 4,0 days, ventilator 72,0 hours and HFV 66,0 hours. 56,1% of the neonates with PPHN received iNO, the median was 74,5 hours. 58,5% needed vasopressor support and 38,4% was not given any sedation. 13 neonates was added to ECMO, median 98,0 hours. In this study 69,2% survived ECMO. The overall mortality of PPHN was 14,0%. Conclusion: PPHN appear to affect more premature and neonates with lower gestational age compared to neonates in the normal population in Norway. It is also several neonates with PPHN who has birth weight < 2000 g and Apgar score < 7 (after 1 and 5 minutes).