Background: It is reported that hyperglycemia is encountered in up to 50% of all ST segment elevation myocardial infarction (STEMI) patients, whereas previously diagnosed DM is present in only 20% to 25% of STEMI patients. Blood glucose level at admission has been reported as a major independent predictor of both in-hospital and long-term outcome regardless of diabetic status in STEMI. The aim of this study was to evaluate whether initial glucose level affects the clinical outcomes in non-diabetic patients with non-STEMI (NSTEMI). Subjects and Methods : We have studied 3740 consecutive non-diabetic patients with NSTEMI, who were registered in Korea Acute Myocardial Infarction Registry (KAMIR) between Oct 2005 to Jun 2007 (64.0짹14.1 years, 2534 males). The patients were divided into three groups according to initial blood glucose levels(Group I: glucose <140 mg/dL, Group II: 140 mg/dL��� glucose <200 mg/dL, Group III: glucose ���200 mg/dL). Cardiac deaths, target-lesion revascularizations (TLR) and composite major adverse cardiac events (MACE) were compared among three groups. Results: In-hospital death increased along with blood glucose level (Group I vs. Group II vs. Group III: 1.4% vs. 5.4% vs. 7.5%, p<0.001) with Chi-square analysis. In Kaplan-Meier survival analysis, Group I showed less MACE rate compared with group III (p=0.006 by Log-Rank test). Cardiac death rate of all three groups were significantly different each other. Group I was better than Group II or Group III (6.3% vs. 16.8% or 25.0%, p<0.001 by Log-Rank test) and Group II was better than Group III (16.8% vs. 25.0%, p=0.049 by Log-Rank test). In analysis of TLR, there were no significant differences between blood glucose groups. With logistic regression, age (p=0.007, OR 1.128, 95% CI 1.033-1.231), blood glucose level(p=0.023, OR 1.014, 95% CI 1.002-1.026) and serum total cholesterol level(p=0.035, OR 1.035, 95% CI 1.002-1.069) were independent predictors of cardiac death in non-diabetic patients with NSTEMI. Conclusion : Lowering blood glucose level may improve adverse outcomes even in non-diabetic patients with NSTEMI as well as patients with STEMI.