Pseudoaneurysm of the right ventricular outflow tract is a rare lesion caused by disruption of the ventricular wall that allows the blood to leak into the surrounding space. It often complicates surgery involving right ventriculotomy and progressively increases in size, therefore causing airway compression, pulmonary perfusion asymmetry, thromboembolism, and rupture. We report on a patient who developed right ventricular pseudoaneurysm early after surgery for atrio-ventricular septal defect with tetralogy of Fallot and needed emergency surgical repair due to low cardiac output and repeat syncopal attacks.