OBJECTIVE: We evaluated the effects of surfactant therapy in acute lung injury (ALI) induced by E. coli lipopolysaccharide (LPS) endotoxin. METHODS: ALI was induced by intratracheal administration of E. coli LPS endotoxin in rats. The study group was treated with E. coli LPS endotoxin (40 mg/kg) and surfactant (100 mg/kg) intratracheally. The controls were intratracheally injected with LPS endotoxin and same dose of 0.9% normal saline instead of surfactant. Before and after endotoxin instillation, we estimated body weight, respiratory rate (RR) and heart rate (HR). The WBC counts had estimated in blood and bronchoalveolar lavage (BAL) fluid, and the total protein values were measured in BAL fluid. And also, we examined IL-1beta, IL-6 values in BAL fluid and serum. Finally, the histopathologic changes were confirmed with light and electron microscopic study. RESULTS: In the study group, the WBC counts had decreased in BAL fluid (p<0.05) and the IL-1beta and IL-6 values had decreased in serum and BAL fluid (p<0.05). But, there were non-significant decrement in WBC counts of blood and the total protein values in BAL fluid (p>0.05). The RR and HR changes after instillation were also non-significant (p>0.05). Morphologically, the light microscopic examination denoted pathological findings such as infiltration of neutrophils and alveolar macrophages, vascular congestion. In electron microscopic study, there were various sized and shaped lamella bodies, and vacuolization of lamella bodies in alveolar type II cell. CONCLUSION: Surfactant protects effectively the ALI caused by LPS endotoxin in vivo and the protective effects of that may be related to anti-inflammatory action.