The nitric oxide pathway plays a pivotal, yet diverse, role in human physiology, including modulation of vascular tone, neural transmission and inflammation. Inhaled nitric oxide is a selective pulmonary vasodilator that has emerged rapidly as an important therapeutic agent. It finds its best applications in paediatrics; the use of iNO in term neonates with hypoxaemic respiratory failure, in the assessment of pulmonary vascular reactivity and in the treatment of postoperative pulmonary hypertension in congenital heart disease is well recognised and accepted. This review details the delivery and monitoring aspects of inhaled nitric oxide, its potential toxic and side effects and its applications in several cardiopulmonary disorders in paediatrics.