Persistent pulmonary hypertension (PPHN) is a disease characterised by the disruption of the transition from fetal to neonatal circulation with the persistence of high pulmonary vascular resistances and right-to left shunting. This condition, occurring in about 1-2 newborns per 1000 live births, causes severe hypoxemia. Despite significant improvements in treatment, the mortality of PPHN varies from 10 to 20 % of affected newborns. Pulmonary hypertension is frequently observed in some cardiac malformation and in congenital diaphragmatic hernia, in meconium aspiration syndrome, neonatal sepsis, podalic presentation and male sex. Maternal risk factors are tobacco smoking, cesarean section, low socio-economic conditions, diabetes and urinary infections. Another predisposing condition is antenatal or postnatal exposure to some drugs. The medications involved in drug-induced pulmonary hypertension and the mechanisms involved are reviewed.