Objectives: This study sought to investigate the impact of aspiration thrombectomy on 1 year major adverse cardiac event(MACE) in patients with ST-segment elevation myocardial infarction(STEMI). Background: Aspiration thrombectomy(AT) could have a beneficial effect on the outcome in patients with acute myocardial infarction. However there were limited data for the safety and effectiveness of thrombectomy in primary angioplasty. Method: We retrospectively analyzed 198 consecutive STEMI patient who underwent primary angioplasty in Eulji hospital within 24 hour after symptom onset from June 1, 2003, to May 31, 2008. A total of 75 patients(37%) were treated with aspiration thrombectomy before angioplsty. MACE were defined as death, repeat myocardial infarctinon, and infarc related artery reintervention. Result: The 1 year MACE was lower in the patient receiving aspiration thrombectomy than in those without (26.7% vs. 10.6%, p=0.02) and beneficial effect remained after adjustment for baseline characteristics (hazard ratio[HR] 0.215, p=0.04). Aspiration thrombectomy was also an independent predictor of a lower 1 year MACE in patients with mutivessel coronary disease (HR 0.631 p=0.04) and patients implanted more than 21mm length stent (HR 0.983, p=0.03). Conclusion: Aspiration thrombectomy lowered 1 year MACE in STEMI. In selected patients with multivessel coronary disease and implanted more than 21mm length stent AT is associated with a lower 1 year MACE rate.