Backgrounds: Early reperfusion after coronary occlusion in acute myocardial infarction is associated a better prognosis. Some patients with non-ST segment elevation myocardial infarction (NSTEMI) showed total occlusion (TO) of infarct related artery (IRA). We investigated the benefits of early invasive management (EIM) for in-hospital outcome (IHO) of patients with NSTEMI with TO of IRA. Methods: A total of 1406 patients (64.7짹12.1 years, male 67.2 %) with NSTEMI who were registered in Korea Acute Myocardial Infarction Registry from Nov. 2005 to Dec. 2007 and underwent percutaneous coronary intervention. The patients were divided into four groups; Group I: TO of IRA, n=368 {Group Ia: TO of IRA and EIM, n=271; Group Ib: TO of IRA and selective invasive management (SIM), n=97}, Group II: non-TO of IRA, n=1038 (Group IIa: non-TO of IRA and EIM, n=627; Group IIb: non-TO of IRA and SIM, n=411). Results: There were no significant differences of Thrombolysis In Myocardial Infarction risk score and baseline characteristics between Group I and Group II. Also, no significant differences of both of them were between the Group Ia and Ib and between Group IIa and Group IIb. Group I had higher level of creatine-kinase MB, troponin I, and Killip class than Group II (p<0.001, p=0.002, p=0.027, respectively). Group I needed longer intensive care (p=0.006) and had higher in-hospital adverse events (IHAE) than Group II (11.7% vs. 6.2%, p<0.001) In subgroup analysis, Group Ia had lower IHAE than Group Ib (5.7% vs. 12.1%, p=0.047) but no significant difference of IHO was between Group IIa and Group IIb (5.6% vs. 6.5%). TO of IRA was associated IHO in patients with NSTEMI. (RR 2.01, 95% CI 1.34-3.02, p=0.001). EIM decreased rate of IHAE in patients with NSTEMI with TO of IRA (RR 0.45, 95% CI 0.19-0.91, p=0.042). Conclusions: TO of IRA in patients with NSTEMI is associated with IHO and EIM improves IHO of patients with NSTEMI who have TO of IRA.