Among all the congenital coronary anomalies, an anomalous origin of the left coronary artery (LCA) from theright sinus of Valsalva is rare. A 48-year-old male patient suffering with lateral acute myocardial infarction was referredfor primary percutaneous coronary intervention. The initial angiogram failed to show the LCA, which originatedfrom the right coronary sinus. A critical stenotic lesion was observed in the distal left circumflex artery. Thelesion was treated successfully with stenting. We report here on a case of an anomalous origin of the left coronaryartery from the right sinus of Valsalva, and the patient presented as acute myocardial infarction. He was successfullytreated with primary percutaneous intervention. (Korean Circulation J 2006;36:817-819)