Coronary artery fistulae are rare and usually discovered as incidentally during coronary angiography. They may be congenital or acquired secondary to trauma or cardiac intervention, and usually involve the left anterior descending or right coronary artery, with the circumflex artery much less often affected. They have been reported in transplanted hearts, usually as a secondary complication to right ventricular biopsies, and typically drain into the right ventricle. We hereby report a case of circumflex coronary artery to the great cardiac vein fistula that we believe occurred after transplantation and spontaneously closed while we were assessing the patient for percutaneous closure of the fistula.