Abstract： Objective To study changes of neuroendocrine in patients with ST segment elevation acute myocardial infarction (STEMI) after using distal protection device (GuardWire PlusTM). Method Seventy patients with STEMI received percutaneous coronary intervention (PCI) in Municipal Hospital Qingdao, during September 2004 to December 2006. They were randomdy (random numbs) enrolled in this prospective and control study. All the patients were divided into 2 groups: the distal protection device group (GW) and the non-distal protection device group (NGW).The inclusion criteria were:onset within 6 hours, chest pain more than 30 minutes without response to nitroglycerin, two or more adjacent ST segnents elevated over 0.2 mv,the proximal or middle diameter of infarction artery over 3 mm, and the increased plasma creatine kinase. The exclusion criteria were fluctuation in hemodynamics, severe heart failure, arteriopathy of left main coronary artery, mechanical complications of acute myocardial infarction and multi-vessel disease scheduled for coronary artery bypass. The plasma levels of endothelin(ET) , plasma renin activity (PRA),aldosterone (ALD),angiotensin Ⅱ (Ang Ⅱ), norepinephrine (NE) and epinephrine (E) were measured on the day of operation and on the 1st,2nd,3rd and 5th day after operation, respectively. The t-test was used to compare those neuroendocrine elements between two groups. Results There were no differences in plasma levels of all the neuroendocrine elements between two groups before operation. Compared with the NGW group, the levels of neuroendocrine elements in the plasma rapidly decreased in the GW group at 1 d after the operation ( P ＜ 0.05). Conclusions In patients with ST segment elevation acute myocardial infarction, the distal protection device can decrease the changes in neuroendocrine.