An extremely rare coronary artery anomaly where the left main coronary artery arose anteriorly from the right coronary sinus and coursed in front of the right ventricular outflow tract was present in a patient with tetralogy of Fallot. Preoperative angiocardiography was interpreted as normal. Operative recognition was prevented by dense adhesions and a partial intramural course. Division of the vessel at repair resulted in death of the patient. The angiographic pattern associated with this anomaly is very unusual, and in many views looks deceptively normal. Details are presented.