Partial liquid ventilation (PLV) with perflurocarbons has been studied for the treatment for acute respiratory distress syndrome (ARDS). The aim of this project is to study the respiratory mechanics, gas exchange, physiologic data and alvelolar morphology of PLV on an animal model with two different perfluorocarbons, Multifluor APF-140 (Air Products, Allentown, PA) and perfluorodecalin (F2 Chemicals Ltd, Lancashire, UK), as compared to conventional mechanical ventilation (CMV). Respiratory failure was induced by repeated saline lung lavage. After achieving a PaO2 <100 mmHg sustained for an hour with CMV, animals were gas ventilated (GV) in the control group (n=7), underwent PLV with Multifluor APF-140 (n=3), or PLV with perfluorodecalin (n=5), for an additional four hours. Physiological data were monitored every 15 minutes and blood gases taken every hour. After the experimental period, the animals were euthanized and the lungs were removed for histological examination. PLV with Multifluor APF-140 improved the gas exchange and presented the lowest general alveolar damage, although it did not improve respiratory mechanics. Perfluorodecalin PLV deteriorated the gas exchange even more than the GV group and intensified alveolar damage. This study suggests that the perflurocarbon used for Pl.V affects the gas exchange efficacy and the type of alveolar damage observed.