Aims This study was undertaken to determine the diagnostic value of admission B-type natriuretic peptide (BNP) for acute myocardial infarction (AMI) in patients with acute chest pain and no ST-segment elevation. Methods and results A prospective study with 631 consecutive patients was conducted in the emergency department. Non-ST elevation AMI was present in 72 patients and their median admission BNP level was significantly higher than in unstable angina and non-acute coronary syndrome patients. Sensitivity of admission BNP for AMI (cutoff value of 100 pg/mL) was significantly higher than creatine kinase-MB (CKMB) and troponin-I on admission (70.8 vs. 45.8 vs. 50.7%, respectively, P < 0.0001) and specificity was 68.9%. Simultaneous use of these markers significantly improved sensitivity to 87.3% and the negative predictive value to 97.3%. In multiple logistic regression analysis, admission BNP was a significant independent predictor of AMI, even when CKMB and troponin-I were present in the model. Conclusion BNP is a useful adjunct to standard cardiac markers in patients presenting to the emergency department with chest pain and no ST-segment elevation, particularly if initial CKMB and/or troponin-I are non-diagnostic.