BACKGROUND: Although exact mechanism of adult respiratory distress syndorme (ARDS) is not known, many evidences suggest that inflammatory mediators such as protease and oxygen radicals may be the final common pathway to the endothelial injury. It is gradually accepted that activated neutrophils play a major role in the process. Pentoxifylline is a methylated xanthine with a wide range of actions that make it theoretically useful in the treatment of ARDS. Studies show that it decreases neutrophil phagocytosis and superoxied production. The aim of this experiment is to determine whether pentoxifylline has a preventive effect on oleic acid-induced lung injury. METHODS: Oleic acid (0.08 ml/kg) was infused in 10 mongrel dogs in order to induce acute lung injury. Pentoxifylline (20 mg/kg) was administered 40 mins before oleic acid injection. The author made a comparative studies on the effects of pentoxifylline on hemodynamics and gas exchange before oleic acid injection and at 15, 30, 45, 60, 90 mins after oleic acid injection. RESULTS: There were not significant changes in mean arterial pressure, cardiac output, systemic vascular resistence, pulmonary wedge pressure intrapulmonary shunt in both groups. There were statistical significance in arterial oxygen tension, pulmonary artery pressure, pulmonary vascular resistance between both groups (p<0.05). CONCLUSIONS: Pentoxifylline is a noteworthy drug that could be a candidate as a therapy to help prevent effect in lung injuries that share a common mechanism with oleic acid-induced lung injury.