Objective This study sought to determine the normal ranges of N-terminal pro-brain natriuretic peptide (NT-proBNP) in normal children and children with symptoms of heart failure (HF) caused by dilated cardiomyopathy (DCM),and further study their clinical implications.Methods Concentrations of Serum NT-proBNP were determined in 80 normal children and 45 children with clinical symptoms of HF.Venous blood was taken in each subject,and plasma NT-pro BNP was determined by ELISA method.Of the 80 normal children,40 were boys and 40 were girls.Their age ranged from 1 to 16 years old with a mean of 10.6?4.2 years.The 45 children with HF ,caused by dilated cardiomyopathy (DCM).Their age ranged from 1 to 16 years,and had a left ventricular ejection fraction (LVEF) of less than 50%.The serum NT-proBNP levels were correlated to LVEF measured by echocardiography and clinical symptom score of heart failure defined by using Ross Score.Results The mean (?s) serum concentration of NT-proBNP was 223.1?76.6fmol/ml in normal children from 1 to 16 years old.NT-proBNP levels did not show a significant age-related or sex-related differences.In children with HF,the plasma NT-proBNP levels were significantly elevated (mean:1353.3 fmol/ml range: 341.6 fmol/ml～2794.1 fmol/ml) as compared to normal children.(P