BACKGROUND: Congenital heart disease may be complicated by pulmonary hypertension. We assessed whether inhaled nitric oxide would produce selective pulmonary vasodilation in pediatric patients with congenital heart disease and pulmonary hypertension. METHODS: Inhaled low dose (10 20 ppm) nitric oxide was administrated in patients who were at risk of pulmonary hypertension after operations for congenital heart disease. To identify the nitric oxide effects, we evaluated hemodynamic and ABGA data before (T0) and after (T1) inhaled nitric oxide and just before (T2) decreasing concentration of inhaled nitric oxide. RESULTS: Inhaled nitric oxide decreased pulmonary arterial pressure and increased PaO2/FiO2 without decreasing systemic arterial pressure. CONCLUSIONS: Inhaled nitric oxide selectively decreased pulmonary arterial pressure in patients with congenital heart disease complicated by pulmonary artery hypertension.