Objective To evaluate the diagnostic value of brain natriuretic peptide (BNP) for cardiac dyspnea.Methods Plasma BNP levels were measured by radioimmunoassay in dyspnea patients with chronic heart failure (CHF) (n=52) or without CHF (n=30) and normal control group (n=28).Results The BNP level in dyspnea patients with CHF was significantly higher than that of dyspnea patients without CHF and normal control group [(649.80±141.72) pg/mL vs (59.08±18.60) pg/mL and (65.20±16.32) pg/mL，respectively,Plt;0.05].There was no significant difference of BNP level between dyspnea patients without CHF and normal group (Pgt;0.05).The plasma BNP level elevated with the worsening of heart failure (NYHA Classiffication).The BNP level in dyspnea patients with CHF was negatively correlated with left ventricle ejection fraction (r=－0.673，Plt;0.001).The receiver operating characteristic (ROC) curve analysis showed that the area under the ROC curve (AUC) is 0.91(0.88-0.98，Plt;0.001) with a sensitivity of 87.2% and a specificity of 86.8% at the cutoff value of 206 pg/mL.Conclusion Measurement of plasma BNP is a rapid diagnostic method for cardiac dyspnea.