In the 1960s and 1970s, pulmonary haemorrhage (PH) occurred mainly in full-term infants with pre-existing illness with an incidence of 1.3 per 1000 live births. Risk factors for PH included severity of illness, intrauterine growth restriction, patent ductus arteriosus (PDA), coagulopathy and the need for assisted ventilation. Presently, PH occurs in 3% to 5% of preterm ventilated infants with severe respiratory distress syndrome (RDS) who often have a PDA and have received surfactant. The cause of PH is thought to be due to rapid lowering of intrapulmonary pressure, which facilitates left to right shunting across a PDA and an increase in pulmonary blood flow. Retrospective case reports and one prospective uncontrolled study have shown promising results for surfactant in treating PH.