ABSTRACT INTRODUCTION Acute respiratory distress syndrome is a complex heterogeneous disorder with low incidence but high case fatality in children. Treatment with pulmonary surfactants is a possible option. Surfacen, a Cuban exogenous pulmonary surfactant, has been proven safe and effective in premature newborns with hyaline membrane disease, but evidence regarding its efficacy in older children is still inconclusive. OBJECTIVE Determine Surfacen’s efficacy in improving oxygenation and increasing survival in children with acute respiratory distress syndrome. METHODS A multicenter (five pediatric intensive care units in four provinces), open-label, controlled, randomized phase III clinical trial with two treatment groups was conducted from November 2009 through August 2013, with 19 girls and 23 boys aged 1 month to 18 years. The experimental group (20 patients) received conventional treatment (oxygenation and mechanical ventilation) plus intratracheal instillation of Surfacen (100 mg/4 mL) every eight hours for three days. The control group (22 patients) received only conventional treatment. The primary dependent outcome was patient vital status (alive or deceased) 28 days after study enrollment. Other variables and outcomes analyzed were age, sex, ARDS presentation, Kirby index (arterial oxygen tension over inspired oxygen fraction), oxygenation index, static lung compliance, transcutaneous oxygen saturation, radiographic course, mechanical ventilation time and length of stay in neonatal intensive care. Statistical tests used were the chi-square test and Fisher exact test. RESULTS On day 28, there was 80% survival in the experimental group versus 38.1% in the control group. There were significant differences between the experimental and the control group in Kirby index, oxygenation index, static lung compliance and radiographic course, all favoring the experimental group. For every 2.38 patients treated in total, there was one additional survivor in the experimental group. CONCLUSIONS When combined with conventional therapy in the regimen employed, Surfacen improves oxygenation and increases survival in children with ARDS.