A 54-year-old man developed unstable angina pectoris and was found to have both an anomalous left coronary artery, which arose from the right sinus of Valsalva and followed an intramyocardial (septal) course, and severe atherosclerotic stenosis of the mid-right coronary artery. Stress perfusion imaging showed ischemia in the distribution of the right coronary artery, leading to successful percutaneous transluminal balloon angioplasty of the right coronary artery rather than surgical correction of the congenital anomaly.