Isolated coronary artery is a rare congenital coronary anomaly, which may be asymptomatic and occasionally detected in patients with myocardial ischemia due to atherosclerotic coronary artery disease. We describe a 77 year-old female patient with unstable angina. The coronary angiogram showed the presence of a single coronary artery arising from the right sinus of Valsalva with a significant stenosis at the left main coronary artery. The stenosis was treated through percutaneous coronary angioplasty with complete relief of symptoms and without evidence of myocardial ischemia at 6-months follow up. Multidetector-row computed tomography (MDCT) was effective for subtle discrimination between different types and provided excellent visualization of the coronary arteries and is therefore helpful in determination of the most appropriate management.