Abstract： Objective To investigate the effect of emergency percutaneous coronary interventional(PCI) treatment on plasma brain natriuretic peptide (BNP) levels and left ventricular remodeling in patients with acute myocardial infarction (AMI). Methods This study included 118 patients with AMI and 20 healthy volunteers (their results were regarded as normal reference). Fifty-two patients who underwent successful emergency PCI 6- 12 hours after onset were named as PCI group, and 66 patients rejected or in whom emergency PCI failed served as the control group. Plasma BNP levels were determined with Triage rapid assay at admission,at 12, 24, 48, 72 hours and 7, 14, 28 days after admission for both groups. Left ventricular ejection function (LVEF) was assessed by echocardiography with the modified Simpson's equation on 3 - 5 days and 28 days. Same assay was performed for 20 healthy volunteers. Results Plasma BNP levels of both groups were significantly higher at admission than those of volunteers. There was significant difference in BNP levels between two groups at corresponding time points (all P＜0.01). In PCI group, BNP level peaked during 12 -24 hours after admission, whereas two peaks of elevation of BNP levels were detected in control group, the first peak appeared during 12 - 24 hours and the second peak on 7 days after admission.Plasma BNP levels in PCI group were significantly lower than those of control group at corresponding time pionts (all P＜0.01). There was no difference in LVEF level between two groups on 3- 5 days after admission. LVEF level after emergency PCI was significantly higher than that of control group on 28 days after admission (P＜0.01). Conclusion Emergency PCI lowers plasma BNP level and improve LVEF level in patients with AMI, and it may reverse ventricular remodeling.