Background: Pulmonary capillary wedge pressure (PCWP) is an established index of cardiac function and an essential component in the management of patients with congestive heart failure and in critically ill patients. There are several echocardiographic parameters reported to be reliable factors to estimate PCWP. Recently, B-type natriuretic peptide (BNP) levels is also reported to increase in systolic and diastolic heart failure. However, whether the value of BNP can predict PCWP is unclear. We investigated whether these parameters including BNP could predict PCWP or not. Methods: We prospectively studied 50 consecutive patients with pulmonary artery catheters. Several echocardiographic Doppler parameters including especially early transmitral velocity/tissue Doppler mitral annular early diastolic velocity (E/Ea) were obtained from transthoracic Doppler echocardiography. Simultaneously, serum BNP level and PCWP estimated by using Swan-Ganz catheter were obtained, respectively. Results: BNP had a correlation of r=0.43 (p=0.02) with PCWP compared with r=0.57 (p=0.01) between E/Ea and PCWP. E/Ea >15 was the optimal cuttoff to predict PCWP >15 mmHg (sensitivity, 85%; specificity, 88%), whereas the optimal BNP cuttoff was >300 pg/mL (sensitivity, 90%; specificity, 55%). In patients with cardiac disease, E/Ea >15 (sensitivity, 90%; specificity, 89%), appeared more accurate than BNP >400 pg/mL (sensitivity, 90%; specificity, 50%), whereas in patients without cardiac disease, BNP (sensitivity, 80%; specificity, 81%) appeared more accurate than E/Ea >15 (sensitivity, 72%; specificity, 70%) for PCWP >15 mmHg. Conclusions: Mitral E/Ea has a better correlation than BNP with PCWP. Both BNP and mitral E/Ea have high sensitivity for PCWP >15 mmHg; however, E/Ea appears more specific in this patient population. In patients without cardiac disease, BNP appears more accurate than E/Ea for PCWP >15 mmHg, whereas E/Ea appears more accurate in patients with cardiac disease.