Introduction.— Real-time transesophageal echocardiography (RT3D TEE) is a recent imaging modality which has been validated against magnetic resonance imaging for the measurement of left ventricular (LV) volumes. If feasibility in ventilated patients in the ICU is not yet known. The main objective of the study was to test the hypothesis that bidimensional (2D) TEE underestimates LV volumes when compared to RT3D TEE. The secondary objective was to evaluate the feasibility of RT3D TEE in ventilated patients in the ICU and to assess the influence of the analysis software on values of LV volumes. Methods.— During a two-month period, patients without cardiac history admitted in the ICU for neurological disorder requiring a mechanical ventilation were studied. A 2D TEE performed by an experienced intensivist ruled out any cardiac abnormality and three loops of RT3D TEE were recorded during an end-expiratory apnea to avoid excessive cardiac translation. Measurements were perA