【Objective】 To investigate the protective effect of dexamethasone on lung injury secondary to intestinal ischemia-reperfusion. 【Method】 Thirty-five male rats weighting 20~24 g were randomized into sham group

sole IIR group (IIR)

or IIR and preconditioning with dexamethasone (II/R+DP)

or II/R+DI group (respectively treated with dexamethasone after ischemia began)

or II/R+DR group (respectively treated with dexamethasone as soon as reperfusion). At the end of experiment

lung tissue was obtained for histologic assessment and for the measurement of the levels of MDA

SOD

TNF-α

NO

and iNOs. 【Result】 IIR resulted in lung injury evidenced as significant decreases in lung histological scores (P < 0.05

IIR vs. S)

accompanied with concomitant increases of the levels of MDA

SOD

TNF-α

NO and the activity of iNOs (P < 0.05

II/R vs. S). Preconditioning with dexamethasone attenuate IIR mediates lung injury(P < 0.05

II/R+DP vs. II/R)

while treated with dexamethasone during the ischemia and reperfusion period were unprofitable to lung. 【Conclusion】 Preconditioning with dexamethasone attenuate IIR mediates lung injury

while treated with dexamethasone during the ischemia and reperfusion period were unprofitable to lung.