Background: N-Terminal Pro-Brain Natriuretic Peptide(NT-proBNP) was introduced recently for useful parameters for assessing left ventricular(LV) systolic function. But there was few reports about assesing left ventricular(LV) diastolc function in symptomatic diastolic heart failure. So we studied about correlation of NT-proBNP and diastolic parameters by transthoracic echocardiography in the patients with the symptom and increased left atrial volume index(LAVI) reflecting chronically elevated LA pressure. Methods: Fifty one consecutive patients with dyspnea on exertion and borderline or increased left atrial volume index(LAVI) was measured various Doppler echocardiographic parameters and NT-proBNP just after echocardiography. Results: Patients (73% Female; mean age 65짹12 years) showed normal LV systolic functions(EF=62.9짹11.3%) and increased LAVI(33.0짹9.7cc). NT-proBNP levels ranged from 5 to 35000 ng/L, with a median of 160.8ng/L (interquatile range, 63 to 335ng/L). NT-proBNP showed significantly correlated with LAVI, Transmitral E/A ratio(E/A), transmitral peak E velocity/mitral annular E��� velocity(E/E���) and systolic fraction of pulmonary venous flow (r=0.372 and P=0.007, r=0.329 and P=0.019, r=0.293 and P=0.037 and r=-0.285 and P=0.043, respectively). And also NT-proBNP showed significantly linear correlation with LV mass index and EF (r=0.417 and P=0.002 and r=-0.347, p=0.013, respectively). Interestingly, NT-proBNP significantly correlates with questionair about capacity for climbing stairs(r=-0.370, p=0.007). Conclusions: NT-proBNP significantly correlates with LV diastolic parameters in symptomatic diastolic heart failure patients and may be useful parameter for assessing their functional capacity.