Oral sildenafil has been demonstrated to be an effective treatment for pulmonary hypertension, and is increasingly used in children. We report an infant with pulmonary hypertension, stable on regular treatment with oral sildenafil, who presented in acute respiratory failure after aspiration, requiring ventilation and intensive care. The course of the stay in intensive care was difficult, with recurrent pulmonary hypertensive crises despite use of oral sildenafil, use of 100% oxygen, high frequency oscillatory ventilation, and inhaled nitric oxide. In view of his instability, and the presumed inability to absorb the sildenafil orally due to gastrointestinal malabsorption, sildenafil was administered as a continuous intravenous infusion. With this therapy, it proved possible to wean from oxygen, nitric oxide, and ventilatory support. Intravenous sildenafil, therefore, might be an effective alternative for children with pulmonary hypertension during episodes of acute deterioration and malabsorption, preventing life-threatening pulmonary hypertensive crises. Its pharmacokinetics, efficacy, and safety, nonetheless, need to be validated in randomized controlled trials.