A false aneurysm of the ascending aorta developed in a 25-month-old male infant with tetralogy of Fallot because of an expanded polytetrafluoroethylene (PTFE) shunt that had been inserted between the ascending aorta and right pulmonary artery when the patient was 3 months of age. Surgical repair of tetralogy of Fallot with ligation of the PTFE graft was performed at 19 months of age. The false aneurysm at the site of the systemic anastomosis to the shunt was discovered 6 months later and was successfully repaired. Because of the potential for graft dehiscence secondary to growth, we recommend that PTFE shunts be removed completely or, at least, ligated and divided at the time of corrective surgical intervention.