Objective. To approach the relation and the possible mechanism between the expression of intercellular adhesion molecule （ICAM1） mRNA and acute lung injury （ALI） and the mechanisms of rhubarb in the prevention and treatment of the lung injury. Methods. Lipopolysaccharide （LPS） was injected into the sublingual vein of male Wistar rats to perform ALI animal model. The rats were divided into 4 groups: LPS group

control group

rhubarb group and dexamethasone group. Macroscopic and histopathological examinations were performed and biological markers were measured for the lung specimens. The markers included lung wet/dry weight

the rate of neutrophils and protein content in the pulmonary alveolar lavage fluid

pulmonary vascular permeability and pulmonary alveolar permeability index. Molecular hybridization method was used to determine the expression of ICAM1 mRNA. Results. In the lung tissues

the ICAM1 mRNA expression was increased in the endothelial cells of pulmonary veins and capillaries

rhubarb and dexamethasone had the action of decreasing the expression. The light reflex value in the gray scale scanning showed that in the comparison between the LPS and the control group

the gray scale value of the lung tissues in ALI was significantly increased

thus the light reflex value was markedly decreased （P<001）

demonstrating the expression of ICAM1 mRNA was increased. In comparison with the LPS group

dexamethasone and rhubarb could decrease the gray scale value of the lung tissue significantly

thus the light reflex value was elevated （P<001

P<005）; the corresponding pathologic changes of lung tissues and the biological markers of the lung injury were significantly decreased or ameliorated. Conclusions. The increase of the expression of ICAM1 mRNA in the lung tissues of ALI plays the roles in ALI. The application of rhubarb and dexamethasone can decrease the expression and ameliorate the lung damage; its mechanism is possibly via the inhibition of ICAM1 mRNA expression.