Forty-eight patients with significant left main coronary artery obstruction underwent coronary artery bypass graft between September,1989 and September,1993. They consisted of 29 males and 19 females with the mean age of 58 [range 33 - 78 . Seventeen patients[35% had stenosis in left main coronary artery only and twenty-nine[61% had associated lesions in other coronary artery systems as well.Two[4% had isolated left coronary ostial lesion. The operative mortality was 4.17% [2/48 which is comparable to the mortality of overall coronary artery bypass surgery cases during the same period[p >0.05 . Perioperative myocardial infarction was occurred in two patients[4.17% . And the infarction rates between the two groups also showed no difference[p >0.05 . The forty-six survivors showed significant improvement in exercise tolerance as well as symptomatology. We conclude that surgery for left main coronary artery disease can be done with no increased risk through careful anesthesia,surgery, and aggressive postoperative care in the critical period.