The comparative studies on operative and hemodynamic results following aorto-coronary bypass grafting were performed in 9 patients with left main trunk (LMT) stenosis and 20 with left main equivalent (LME). One of 20 LME had bypass grafts occluded on the postoperative angiogram. There were two operative deaths, one in LMT, another in LME, and one late death. Following results were obtained in 8 LMT (Group I) and 15 LME (Group II) whose all bypass grafts were patent. There were significantly higher operative mortality rate and the incidence of perioperative myocardial infarction in Group I (11.1% versus 5.0%). Cardiac index and left ventricular ejection fraction significantly increased postoperatively in both groups. Mean Vcf and PLVSP/LVESV significantly increased postoperatively in Group II, but not in Group I. Left ventricular anterior segmental wall motion significantly increased in both groups and apical in Group I, whereas it did not in the postero-inferior segment. The completely revascularized patients had a better postoperative left ventricular function comparing with the incompletely revascularized patients. Angina disappeared postoperatively in all patients in Group I and 12 (75%) in Group II. In both groups, NYHA classification was improved from class III or IV preoperatively to class I or II postoperatively. Postoperative 8 years actuarial survival rate was 88.2% in Group I and 84.6% in Group II. In conclusion, it was suggested that much more strict perioperative management and complete revascularization were needed in the patient with LMT.