Coronary artery fistulas are rare anomalous communications, between coronary arteries and cardiac chambers and great vessels. They are often congenital, but usually present in adulthood. They can affect cardiac haemodynamic stability and are thought to predispose patients to heart failure, myocardial ischaemia, myocardial infarction, infective endocarditis, arrythmias and rupture. Herein, a case is discussed where a patient with long-standing stable angina was found to have a coronary artery fistula to the main pulmonary artery and concomitant ischaemic heart disease with a chronically occluded left anterior descending artery, proximal to the fistula. It is thought that the fistula probably predisposed the patient's ischaemic heart disease. He underwent a successful coronary artery bypass grafting plus surgical ligation of the coronary artery fistula. This uncommon coronary artery anomaly, presenting with ischaemic heart disease, a common disease in adulthood, is discussed in the context of current recommedations.