BACKGROUND AND OBJECTIVES: An early invasive strategy with coronary angiography and revascularization is currently the recommended treatment for patients at high risk with an acute non-ST-segment elevation myocardial infarction (NSTEMI). In this early invasive strategy, percutaneous coronary intervention (PCI) is generally recommended within 48 hours, but there is little data on earlier intervention in intermediate risk patients. SUBJECTS AND METHODS: We studied retrospectively the past medical records of 118 patients at intermediate risk that were admitted at Pusan National University Hospital and were stratified by the time interval from chest pain onset to PCI (Group I: <24 hr; Group II: 24-48 h; Group III: >48 h). Clinical outcomes were evaluated in terms of in-hospital and 12 months follow-up of a major adverse cardiac event (MACE). RESULTS: Baseline characteristics were not different statistically among the three groups, except for the use of tirofiban. There were no in-hospital deaths or myocardial infarctions (MI) in Group I and Group II patients, but there were three cases of in-hospital deaths in Group III patients. The incidence of a 12-month MACE was 0% in Group I patients, 6.7% (one revascularization) in Group II patients and 17.1% (3 deaths, 3 MIs, 7 revascularizations) in Group III patients (p=0.043). CONCLUSION: In acute NSTEMI, the incidence of a 12-month MACE was lower in the intermediate risk group when PCI was performed in the early period. Early PCI could be recommended in acute NSTEMI on the basis of the status of individual patients.