Abstract: Objective To evaluate the value of plasma brain natriuretic peptide (BNP) level for differentiating eardiogenie dyspnea from pulmogenic dyspnea.Methods The detection of plasma BNP was carried out in 248 patients with dyspnea.The apparatus was the CENTUR type chemiluminescence detection produced by the Bayer companies of USA.All patients were divided into three groups depending on disease severity.The level of plasma BNP in each group wag compared.Results The level of plasma BNP in pulmonary disease complicated with left ventricular dysfunction was higher than that of pulmonary disease non-complicated with left ventricular dysfunction.There was significant difference between two groups (χ²=25.597,P<0.001).The level of plasma BNP in pulmonary disease complicated with right ventricular dysfunction was higher than that of simple pulmonary disease.There was no significant difference between two groups (t=1.614,P>0.05).The level of plasma BNP in pulmonary disease complicated with left ventricular dysfunction was higher than that of pulmonary disease complicated with fight ventricular dysfunction.There Was significant difference between two groups (t=2.53 l,P<0.05).If the left ventricular dysfunction degree was notable,the level of plasma BNP waft,high.There was also significant difference in different cardiac function classification by New York Heart Association (χ²=29.463,P<0.001).Conclusion Plasma BNP analysis is an impotent method for differentiating cardiogenic dyspnea from pulmogenie dyspnea.Meanwhile,it is also helpful to evaluating the severity of pulmonary disease complicated with left ventricular dysfunction.