Background The beneficial effect of primary angioplasty of acute myocardial infarction(PAMI) was demonstrated. With risks of microvascular embolization of thrombus, restored coronary blood flow is not always means myocardial perfusion. The aim of this study was to test compare the effect of thrombus aspiration to conventional primary angioplasty. Methods and Results The subjects were 73 consecutive patients underwent PAMI within 12 h of onset of symptom by AMI between January 2005 and June 2006. Patients were divided to two groups; conventional angioplasty(CA, n=50) and thrombus aspiration(TA, n=23). Decision of thrombus aspiration was based on diagnostic angiogram showing high risk of distal micro-embolization; total occlusion, visible large/multiple thrombi, large vessel over 4 mm. After thrombus aspiration, angioplasty and stent deployment were done as CA. Even the more risky profile of the lesion in TA group, the initial results were comparable. Thrombolysis and Myocardial Infarction(TIMI) score of 3 was obtained in 45 lesions(90%) in CA group and 20 (87%) in TA group. TIMI myocardial perfusion(TMP) score 3 was obtained in 54% in CA group and 52% in TA group(p>0.05). Platelet GP IIb/IIIa inhibitor was used in 2 cases each. Major cardiovascular events at 30 days were not significantly different. Conclusions Thrombus aspiration during PAMI seems to improve initial even in high risk lesion profile