Nitric oxide has recently been introduced to the world of neonatal pulmonary medicine. The discovery of endogenous nitric oxide production has stimulated extensive research into vascular biology to find the relation of nitric oxide to the transition of circulatory patterns at birth. Persistent pulmonary hypertension of the newborn (PPHN) has long been recognized as a neonatal complication to a variety of disorders. Traditional treatments for PPHN have been associated with adverse effects. Nitric oxide is considered the only selective pulmonary vasodilator to date. Nitric oxide therapy does not produce systemic hypotension, often associated with the use of intravenous vasodilators. This new therapy may possibly reduce or eliminate the need for invasive life-saving procedures such as extracorporeal membrane oxygenation. This article discusses in great detail nitric oxide chemistry and physiology and the procedure for nitric oxide delivery by inhalation and reviews the results of recent research.