Isolated and severe left main coronary ostial stenosis is a rare case. In the majority of these patients ostial stenosis was associated with any of the conditions known to involve the coronary ostia. These conditions include syphilitic aortitis, Takayasu's aortitis, familial hypercholesterolemia, and aortic valve disease. A 34-year young female patient was presented with exertional and stabbing anterior chest pain. There was no history of syphilis, diabetes mellitus, hypertension, hyperlipidemia and smoking. Coronary angiogram showed isolated left main coronary ostial stenosis. Transesophageal echocardiography(TEE) showed acute angle takeoff of the left main coronary artery. She underwent surgical angioplasty of coronary ostia with a patch of autologous pericardium. After angioplasty, TEE showed dilatation of left main coronary ostium and her clinical symptom improved.