Inhaled nitric oxide (NO) is used in the management of all causes of pediatric pulmonary hypertension. Despite widespread use of nitric oxide to treat critically ill mechanically-ventilated pediatric patients with pulmonary hypertension, response to therapy is not universal. Nitric oxide fails to improve oxygenation in approximately 30% of these patients. Nonresponders to nitric oxide have few treatment options. Iloprost is the only other medication approved for inhalational delivery in the treatment of pulmonary hypertension. Inhalation therapy for pulmonary vasodilatation in critically ill children is inherently more attractive than oral or intravenous therapies due to the ability to deliver medication directly to the lung and to decrease systemic effects. The use of inhaled iloprost has been reported to decrease pulmonary vascular resistance in many pediatric pathologic settings, including combination therapy with nitric oxide.