Objective To investigate the expression of FLIP in the lung of rats and the protective effect in development of acute lung injury( ALI) with the adenovirus vector carrying FLIP gene( Ad-FLIP)inhaled. Methods Forty-eight rats were randomly divided into four groups, with 12 rats in each gruop. In treatment group, ALI rats model was eatablished by LPS intraperitoneal injection and then inhaled Ad-FLIP vector. In prevention group, the animals were infected with Ad-FLIP vector before ALI model wasestablished. Two control groups of treatment and prevention received Ad-EGFP vectors respectively.Pathological changes of lung were observed under light microscope. Wet/dry weight ( W/D) of lung lobes and lung permeability index( LPI) were also measured. The mRNA and protein expressions of FLIP in lungwere investigated by RT-PCR and immunohistochemistry, respectively. Results Lung histopathological changes were alleviated, the index of W/D and LPI were significantly lower, the expressions of FILP mRNA and protein in the lung were elevated both in the treatment group and prevention group compared to thecontrol groups ( all P lt;0. 01) . Conclusion Ad-FLIP transfection can up-regulate the expression of FLIP in lung of rats, and might protect respiratory membrane and lessen pulmonary edema to prevent the development of ALI.