Abstract： Objective To evaluate the effect of thrombus-aspiration during emergency percutaneous coronary intervention(PCI)in patients with acute ST segment elevation myocardial infarction(STEMI). Methods The STEMI patients underwent emergent PCI from 1 October 2007 to 30 November 2008. 40 patients received PCI and aspiration thrombectomy were enrolled in study group and 43 patients who only received routine PCI were enrolled in control group. TIMI myocardial perfusion(TMP) , CTFC, ST-segment declining in 2 h, left ventricular ejection fraction ( LVEF) and major adverse cardiac event(MACE)after operation and the follow-up data were compared between the tow groups. Results TMP 2-3 was achieved in 90.0% of patients in thrombus aspiration group and in 69. 8% in the control group(P <0.05). The thrombus aspiration group had more CTFC [ (30. 3±8. 1) vs(43.1±7.6),t=7.43, P<0.01]and faster ST segment declining in 2 h[(92.5% vs 65. 1% ), x2 =9. 15, P <0.01] than the control groups. The total MACE were 2. 5% in the study group and 9. 3% in the control group after 1 year(P >0. 05). Compared with control group, LVEF of the study groups were improved [ (56. 3 ±2. 9% vs 53. 7±3. 1% ,58.1 ±2. 5% vs 54. 6 ± 2. 9% , 62. 4±2. 7% vs 58. 7 ± 3. 2% ) ] in the follow-up (P > 0. 05 ). Conclusions Thrombus-aspiration is safe and effective, which can improve myocardial reperfusion and ST-segment declining in 2 h, abate MACE in STEMI.