Patients with increased pulmonary vascular resistance may experience acute pulmonary hypertension after heart transplantation. Pulmonary vasodilator drugs usually are delivered by the intravenous or the endotracheal route during acute pulmonary hypertensive crisis. Oral pulmonary vasodilators have a potential role in less acutely ill patients with increased pulmonary artery pressure after heart transplantation. We describe the 1st successful post-operative use of oral sildenafil for pulmonary vasodilation in a patient after heart transplantation.