Purpose: NT-pro B-type natriuretic peptide (NT-proBNP) has predominantly ventricular origin, produced and released in response to increases in ventricular wall stress. It has been related both to systolic and diastolic left ventricular (LV) dysfunction. The purpose of this study was to investigate the correlations of NT-proBNP levels with echocardiographic measurements in patients with systolic heart failure. Methods: We prospectively investigated patients with symptoms/signs of CHF class II-IV and LV biplane ejection fraction (EF)<45%. After clinical evaluation an echocardiogram was done including M mode, 2D (ventricular dimensions and LV ejection fraction (EF)), conventional Doppler (LV inflow E wave, pulmonary artery systolic pressure (PASP), LV dP/dT). Early and late peak systolic myocardial velocity (Sm1 and Sm2), velocity time integral of Sm(SmVTI), early(Em) and late (Am) peak diastolic myocardial velocities were assessed by pulsed tissue Doppler of septal and lateral mitral annulus and tricuspid annulus. Blood was collected for NT-proBNP measurement. Results: Twenty patients were included 85% male, 71±9,5 years. Mean LV EF was 30±8%, dP/dT 557±164mmHg/s, NT-proBNP 7052±6314pg/mL. There was a trend toward higher NT-proBNP levels in those patients with lower inferior vena cava (IVC) colapse index (p=0,09) and a nonsignificant higher expiratory IVC diameter (p=0,15). Right ventricular end-diastolic dimension by 2D planimetry of four-chamber apical view showed a significant direct correlation to NT-pro-BNP levels (r2=0,24; p=0,03) as did PSAP (r2=0,37; p=0,009). No significant correlation was found with tissue Doppler measurements of tricuspid annulus. There was a trend to lower mitral E-wave deceleration time (r2=0,15; p=0,09) in patients with higher NT-pro BNP. No correlation was found to dP/dT and there was a nonsignificant trend to lower LV EF (p=0,07) in those with higher natriuretic peptides. Sm VTI of septal mitral annulus inversely correlated to NT-proBNP (r2=0,20; p=0,049). No other tissue Doppler measurements showed a signicant relation. PSAP was the only independent predictor of NT-proBNP in multiple regression analysis (p=0,029). Conclusion: NT-proBNP level relates to right ventricular dimention and PSAP in systolic heart failure patients. This relation sugests that right ventricular secretion of NT-proBNP may be an important contributor to serum levels of this natriuretic peptide in patients with systolic heart failure. Septal mitral annulus Sm VTI may be a more accurate estimate of global systolic function since it may be under influence of both the right and left ventricle.