Respiratory failure in term newborns is associated with significant morbidity and mortality, despite maximal conventional therapy. Neonates with pulmonary hypertension have been treated with iNO, a selective pulmonary vasodilator. This multicenter, double-masked placebo-controlled randomized trial tested whether iNO would reduce the risk of death and/or the initiation of extracorporeal membrane oxygenation (ECMO) in a prospectively defined cohort of term or near-term neonates with hypoxic respiratory failure unresponsive to conventional therapy. The sample size was based on a reduction of the primary event (death or ECMO) from 50 percent to 30 percent; 90 percent power; and a two-tailed Type I error of 0.05.