Background: N-Terminal Pro-Brain Natriuretic Peptide(NT-proBNP) has been introduced recently as a useful parameter for assessing left ventricular(LV) systolic function. But there were few reports about its usefulness in the symptomatic diastolic dysfunction. So we assessed the hypothesis that NT-proBNP correlates with diastolic and functional parameters in the patients with symptomatic diastolic dysfunction. Methods: 141 consecutive patients who complained dyspnea on exertion and showed abnormal LV filling pattern but preserved or normal LV systolic function were participated. We examined NT-proBNP, various echocardiographic systolic and diastolic functional parameters and functional capacity for climbing stairs at the same time. Patients with ischemic or valvular heart disease, atrial fibrillation and more than 1.5mg/dl of serum creatinine were excluded. Data are expressed as means 짹 standard error of mean or median(25th percentile-75th percentile). Results: Patients(66.0% female, mean age 63.3짹0.9 years, 63.0% hypertensive) showed normal LV systolic functions(EF=65.8짹0.7%) and increased left atrial volume index(32.8짹0.9cc/m²). NT-proBNP levels ranged from 5 to 3716ng/L with a median of 124.0ng/L(interquatile range, 55 to 332ng/L). NT-proBNP showed significant correlations with transmitral peak E velocity/mitral annular E��� velocity, left atrial volume index, pulmonary venous systolic fraction and transmitral E/A ratio(r=0.313 and p=0.000, r=0.309 and p=0.000, r=-0.269 and p=0.002 and r=0.213 and p=0.012, respectively). And as we expected, NT-proBNP showed significant correlations with LV ejection fraction and LV end diastolic dimension(r=-0.282, p=0.001 and r=0.168 and p=0.048, respectively). Interestingly, NT-proBNP significantly correlated with New York Heart Association functional class and capacity for climbing stairs(r=0.309, p=0.000 and r=-0.209 and p=0.014, respectively). Conclusions: NT-proBNP may be a useful parameter for assessing the diastolic function and the functional capacity as well as the systolic function in the patients with symptomatic diastolic dysfunction.