Coronary artery fistula (CAF) is a rare anomaly of the coronary artery. Patients with this condition are usually asymptomatic. However, cardiac failure may occur later in life due to progressive enlargement of the fistula. Diagnosis is traditionally made by echocardiogram and conventional angiogram. However with the advantage of new technologies such as computed tomography (CT) coronary angiography, the course and communications of these fistulae can be delineated non-invasively and with greater accuracy. We report a case of a left circumflex artery fistula to the coronary sinus which was suspected on echocardiogram and the diagnosis was clinched on ECG-gated CT.