The presence of a congenital anomaly in coronary arteries can be the cause of a defective coronary flow and ischaemic symptoms. Although they are rare, we must suspect them in the presence of major cardiac events in young people. A single coronary artery is present if the entire coronary system arises from a solitary ostium. Its presence is regarded as having little clinical significance and it is usually a fortuitous finding on coronary angiography. We report the case of a patient with effort anginal symptoms, with a single coronary artery arising from the right sinus of Valsalva without obstructive atherosclerotic lesions.