Tetralogy of Fallot (TOF), the most common cyanotic congenital heart disease, is classically associated with decreased pulmonary blood flow. Classical TOF is characterized by antegrade pulmonary blood flow and right ventricular outflow tract obstruction at varying levels. In the modern era, most children with TOF undergo definitive intracardiac repair during infancy, and pulmonary artery hypertension (PAH) is virtually unheard of in postoperative TOF in the absence of major aortopulmonary collaterals. We report the circumstances in which PAH can occur after definitive repair of classical TOF in the modern era.