Background and Objectives: The current guidelines recomend an early invasive strategy for patients sufering with non-ST segment elevation myocardial infarction (NSTEMI). However, there is still debate about the timing of revascularization in patients with NSTEMI. To analyze the clinical eficacy of the timing of revascularization, we compared the in-(KAMIR) betwen the early and selective invasive therapeutic groups. Subjects and Methods: Betwen Nov. 2005 and Apr. 207, 2762 acute NSTEMI patients (mean age= 64.6?12.8 years, 1847 males) were enroled in the KAMIR. The therapeutic strategy of NSTEMI was categorized into early invasive treatment (within 48 hours, Group I mean age: 63.1?13.1 years, 1085 males) and selective invasive treatment (Group II mean age: 66.5?12.1 years, 762 males). The initial clinical status and the in-groups. The in-hospital outcomes were also compared betwen the two groups acording to each level of the Throm-bolysis In Myocardial Infarction (TIMI) risk score. Results: There were significant diferences in the mortality and morbidity rate between the groups (6.5% vs. 10.3%, respectively, p<0.001). Acording to TIMI risk score, there were no significant diferences of mortality and morbidity for the low to moderate risk patients (5.3% vs. 7.8%, respectively, p= 0.123 for the risk score 0-2, 6.4% vs. 8.7%, p=0.139 for the risk score 3-4). Conclusion: Early in-vasive treatment improves the hospital outcome for the high-risk NSTEMI patients. The use of abciximab, a low ejection fraction, a high Killip class, a high TIMI risk score and old age are the predictive factors of in-hospital mortality and morbidity.