Decreases of antioxidant enzyme activities (SOD, glutathione peroxidase (GSH-Px), CAT, and total antioxidant capacity (T-AOC)), as well as increases of the ROS levels and the lipid product contents (MDA), were observed in ALI mice in comparison with the normal control (NC) group to a certain extent, indicating that serious oxidative stress of the lung could be induced by the zymosan injection. This evidence concerns the gene SOD1 and acute respiratory distress syndrome.