Effect of ventilation in the face-down position (VFDP) on the oxygenation function of the lungs and hemodynamics is studied in 32 patients (aged 22-64 years) subjected to open-heart surgery complicated by development of acute respiratory failure (RF). In 23 patients with grave respiratory distress syndrome, VFDP was performed with forced ventilation of the lungs (FVL) and in 9 with less grave RF, with noninvasive mask ventilation of the lung (NIMVL). Body position of patients on FVL was changed every 4-12 h, of nonintubated patients, 45-60 min. The oxygenation function of the lungs improved in the intubated patients as early as during the first hour of FVL in the face-down position: PaO2/FiO2 notably increased and a tendency to decrease of A-aDO2 and Qs/Qt was observed. The positive effect was maximal after at least 4-hour FVP in the face-down position: PaO2/FiO2 increased by 76.6%, intrapulmonary shunting fraction decreased by 43%, and the O2 alveolar-arterial difference decreased by 27% in comparison with the initial values. After body position of patients was changed, the above improvements did not disappear, despite a slight decrease of the effect attained. VFDP with NIMVL led to similar results: O2 alveolar-arterial gradient decreased, PaO2/FiO2 decreased by 24.2%, the mean values of this ratio approaching the norm. Positive effect somewhat decreased after catecholamines were discontinued, but the oxygenation function of the lungs remained better than initially.