A young child with exertional chest pain, and an electrocardiographic pattern suggesting reversible ischaemia of the anterior ventricular wall documented by Cardiolyte stress-testing, underwent cardiac catheterization and selective coronary angiography. Although the coronary arteries were entirely normal, the recirculation phase demonstrated marked dilation of the coronary sinus, with atresia of its mouth. At surgery, the patient was confirmed to have muscular atresia at the mouth of the coronary sinus, and underwent unroofing of the coronary sinus to the left atrium, with ligation of a persistent left superior caval vein. Post-operatively, the patient continued to have persistent chest pain, albeit without inducible ischaemia on stress-testing.