Objective To investigate the effect of intravitreal injection with dexamethasone on leukocyte accumulation, vascular permeability, and the expression of intercellular adhension molecule (ICAM-1) in rats with diabetes. Methods Seventy-two BN rats were divided into 4 groups: control group, diabetes group, diabetes+ physiologic saline group, and diabetes+ dexamethasone group, with 18 rats in each group. Streptozotocin was injected into the rats to set up the diabetic model. Accumulated leukocytes were counted in vivo by acridine orange leukocyte fluorography, and retinal vascular permeability was measured by Evans blue assay. The expression of mRNA and protein level of ICAM-1 were evaluated by real-time quantitative polymerase chain reaction analysis and enzymelinked immunosorbent assay. Results In the diabetes+ dexamethasone group, accumulated leukocytes were reduced, retinal vascular permeability decreased, and the expression of ICAM-1 decreased. The expression of ICAM-1 mRNA and protein levels in control group, diabetes group, diabetes+ physiologic saline group, and diabetes+ dexamethasone group were 0.43plusmn;0.07，0.76plusmn;0.21，0.74plusmn;0.18，and 0.55plusmn;0.13; (37.90plusmn;4.56), (76.74plusmn;6.68), (74.32plusmn;7.11), and (39.61plusmn;4.47) pg/mg respectively. Conclusions Dexamethasone can reduce accumulated leukocytes and retinal vascular permeability, which may be caused by inhibiting the expression of ICAM-1. (Chin J Ocul Fundus Dis,2007,23:273-276)