A female infant, born at 33 weeks' gestation with tetralogy of Fallot, died of severe perinatal asphyxia 6 hours after birth. Necropsy disclosed two associated vascular anomalies: a right aortic arch with a left common carotid artery arising from the pulmonary artery (isolated left common carotid artery) and an aberrant left subclavian artery arising from the descending aorta. Agenesis of the thymus and parathyroid gland was also found, suggesting that the child also had DiGeorge syndrome. Origin of the left common carotid artery from the pulmonary artery is exceedingly rare. When planning surgical treatment it is important to be aware of the possibility of this anomaly occurring in association with congenital heart disease, particularly in the presence of tetralogy of Fallot, right sided aortic arch, or DiGeorge syndrome.