Animal studies, uncontrolled case reports and case series suggested a potential benefit to exogenous surfactant replacement therapy in PARDS . However, clinical trials of exogenous surfactant outside of the neonatal population provided mixed results. Nonrandomised studies showed improved oxygenation but no effect on mortality in paediatric patients with moderate-to-severe ARDS according to the NAECC criteria. Calf lung surfactant (calfactant) was compared to placebo in a large, multicentre, randomised, placebo-controlled, masked trial in 153 children with acute lung injury . Surfactant administration significantly improved oxygenation and reduced mortality (19% vs 36%) compared with placebo. However, this beneficial effect of surfactant disappeared after adjusting for immunocompromised state in multivariate analysis. The same group of investigators joined an international, multicentre, placebo-controlled trial comparing calfactant with placebo in both adult and paediatric patients with direct lung injury . The trial utilised a novel form of surfactant, which was twice as concentrated as traditional calfactant. However, the trial was stopped prematurely due to futility. Recent attempts on identifying a possible role for exogenous surfactant through a multinational, prospective, blinded, randomised, controlled phase II trial of intratracheal instillation trial using a synthetic formulation of surfactant (lucinactant) among infants less than 2 years of age also showed no effect on patient outcome .