Abstract： Objective To obselwe the changes of plasma Brain natriuretic peptide(BNP)in patients with acute coronary artery syndrome(ACS)after percutaneous coronary intervention(PCI)or medical therapy.Methods Thirty-seven ACS patients with percutancous coronary intervention(PCI)were enrolled;meanwhile,58 patients with medical treatment were established as a medical group,with 41 healthy persons as a control group.Enzyme-linked immunoadsorbent assay(EUSA)method was used for detecting the concentration of plasma BNP.Blood BNP samples were respectively collected on admission,3rd day,5th day and 10th days after admission.Results The plasma BNP levels in PCI group and medicine group were all significantly higher than control group on admission,3rd day,were 5th day(P＜0.05).But no significant differences were shown among the 3 time points within the two study groups(P＞0.05).On the 10th day,the plasma BNP level in PCI group and medicine group all decreased,but were still significantly higher than control group(P＜0.05). Meanwhile,there were no significant differences of plasma BNP level between PCI group and medicine group on admission,3rd day,5th day(P＞0.05).Conclusion The plasma BNP in patients with ACS increased during the first week.It decreased but remained an insignificant higher level at the 10th day than normality.PCI and medical therapy showed the same effect on plasma BNP level in patients with ACS.