The aim of this study was to determine the advantages of partial liquid ventilation with perfluorocabons (PLV) over conventional mechanical ventilation (CMV) in an ovine model of acute respiratory distress syndrome (ARDS). Methods: Lung injury was induced by saline pulmonary lavage in sixteen young sheep, determined by PaO2<100mmHg maintained for 1 h. For the next 4 h the control group (n = 8), was maintained on CMV, while the PLV group (n = 8) received perfluorocarbon to the functional residual capacity and drained afterwards. Physiologic variables were monitored throughout the experiments. The lungs were removed and tissue injury was assessed by light microscopy. Preliminary Results: PLV provided effective improvement in gas exchange measured by the alveolo-arterial PO2 difference without adverse hemodynamic effects and less intense but equally diffused damage in the lower lobes, when compared with CMV. Further experiments are being conducted to verify these results.