This report describes a 35-year-old woman with unruptured aneurysm of the left sinus of Valsalva presenting as non-ST elevation myocardial infarction due to the compression of the left coronary artery by aneurysm. Cardiac multislice CT and angiogram revealed a large aneurysm of the left sinus of Valsalva compressing the left main coronary artery. Surgical repair was performed by closing the entrance of the aneurysm and aortic valve replacement. Postoperative coronary flow was restored and thus anginal symptom disappeared.