Infants with a large patent arterial duct (PDA) may develop signs of congestive heart failure secondary to pulmonary overcirculation. As the PVR decreases, the relative pulmonary blood flow (Qp:Qs) increases and this may cause tachypnea, respiratory distress, failure to thrive, ventricular dysfunction and even ventilator dependency. The diastolic runoff from the systemic circulation may result in intestinal hypoperfusion resulting in necrotizing enterocolitis, and in severe cases, myocardial ischemia. Cardiac ischemia due to coronary steal is a recognized clinical entity. We present two cases of infants who developed coronary artery steal with the use of supplemental oxygen therapy during anesthesia induction for PDA occlusion. These cases highlight the importance of prudent use of supplemental oxygen therapy in infants with large PDAs. © 2012 Wiley Periodicals, Inc.