Invasive hemodynamic monitoring with Swan-Ganz catheterization to guide treatment decisions in heart failure may be hazardous and may lack prognostic value. We assessed the clinical utility of B-type natriuretic peptide (BNP) in estimating left ventricular filling pressures in patients with inconclusive tissue Doppler indexes. In this study, 50 patients with systolic heart failure and an early transmitral velocity to early diastolic mitral annular velocity ratio (E/Ea) between 8 and 15 were studied. Among them, 25 had been admitted for acutely decompensated heart failure (group A) and the remainder were clinically stable outpatients (group B). All patients underwent simultaneous invasive pulmonary capillary wedge pressure (PCWP) determination, BNP measurement, and echocardiography. In group A, BNP correlated with PCWP (r = 0.803, P < 0.001), deceleration time (DT, r = -0.602, p = 0.001), and end-systolic wall stress (SWS, r = 0.565, P = 0.003). In multivariate analysis, BNP was the only parameter independently associated with PCWP (P = 0.023). In group B, no correlation was found between BNP and PCWP or SWS, while DT correlated significantly with both PCWP (r = -0.817, P < 0.001) and BNP (r = -0.8, P < 0.001). We conclude that BNP may be a useful noninvasive tool for the assessment of left ventricular filling pressures in patients with acutely decompensated heart failure and inconclusive tissue Doppler indexes.