The ratio of tricuspid peak early inflow velocity to peak early diastolic velocity of the lateral tricuspid annulus (the E/Ea ratio) measured by transthoracic echocardiography has been reported to correlate with right atrial (RA) pressure. In this study, the correlation between the E/Ea ratio and RA pressure was tested in 44 anesthetized, paralyzed, and mechanically ventilated patients by transesophageal echocardiography. Mean RA pressure and the following echocardiographic data were recorded simultaneously: tricuspid peak early inflow velocities by Doppler echocardiography, peak early diastolic velocity of the lateral tricuspid annulus by tissue Doppler imaging, and right ventricular and left ventricular end-diastolic areas. Linear regression did not indicate a correlation between the E/Ea ratio and RA pressure (r = -0.11, p = 0.48) or between the E/Ea ratio and the right or left ventricular end-diastolic area index; it revealed a weak correlation between RA pressure and the inspiratory plateau pressure and body mass index. In conclusion, the E/Ea ratio failed to predict RA pressure or planimetric indexes of ventricular preload in anesthetized, paralyzed, and mechanically ventilated patients. In these patients, RA pressure was largely influenced by extracardiac factors.