Background: In ACS, The level of the inactive brain natriuretic peptide (BNP) is a strong predictor of mortality. But most patients were AMI, Non-ST MI or high risk patients with ACS, which were anticipated elevated BNP levels. Therefore we assessed the relationship between BNP level s and long-term prognosis in low risk patients with unstable angina. Methods: BNP was measured in baseline serum samples from 159 patients referred for angiography because of symptoms or signs of coronary heart disease. Unstable angina was defined as a clinical decision with significant coronary artery narrowing ( 50 % luminal diameter) and low grade were defined as patients without presence of the evidence of ST depression or elevation and abnormal Q wave, elevated cardiac enzyme (Troponin I or CK-MB), and abnormal LV function (EF < 45% and pseudonormal or restrictive pattern) or regional abnormality by echocardiography. BNP was checked by Biosite. The adverse cardiac events were defined as attack of myocardial infarction or heart failure and cardiovascular death.Results: Mean age was 62.6 짹 9.8, and male was 81 (50.9%). The proportion of coronary artery disease were 1 vessel 92 (62.2%), multi-vessel 56 (37.7%). Patients with performing PCI were 138 (86.8%). The mean follow-up duration was 32.2 months and 9 patients (5.6%) had died due to cardiac cause and 6 patients (3.4%) readmitted due to heart failure and there was no attack of myocardial infarction. The mean BNP level was 88.7 짹 181.3 pg/mL The mean BNP level was not different in patients with adverse cardiac event or not (197 짹 272.0 vs. 77.4 짹 116.5 pg/mL, p=0.1). Patients with adverse cardiac event were older, smoker and had a history of diabetes and cerebrovascular accident (p<0.05). Multivariate analysis showed that the prognosis were related age and history of cerebrovascular accident (p<0.05). BNP was not related the long-term prognosis (p>0.05). Conclusion BNP is not useful prognostic factors of long-term mortality in patients with low risk unstable angina