Purpose: To understand the expression and distribution of intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1(VCAM-1)and CD45 (Leukocyte Common Antigen) in the control nondiabetic and various courses of diabetic rats retina. To explore the role of adhesion molecules (AMs) and the adhesion of leukocytes to vascular endothelial cells via AMs in diabetic retinopathy(DR).Methods: Sixty healthy adult male Wistar rats were randomly divided into diabetic groups (induced by Streptozotocin, STZ) and normal control groups. Rats in these two groups were further randomly divided into 3, 7, 14, 30, 90 and 180 days-group, including 5 rats respectively. The immunohistochemical studies of ICAM-1, VCAM-1 and CD45 were carried out in the retinal digest preparations or retinal paraffin sections, and the results were analyzed qualitatively, semi-quantitatively.Results: No positive reaction of VCAM-1 was found, and weak reactions of ICAM-1, CD45 were found in nondiabetic rats retina. The differ Purpose: To understand the expression and distribution of intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1) and CD45 (Leukocyte Common Antigen) in the control nondiabetic and various courses of diabetic rats retina. To explore the role of adhesion molecules (AMs) and the adhesion of leukocytes to vascular endothelial cells via AMs in diabetic retinopathy (DR). Methods: Sixty healthy adult male Wistar rats were randomly divided into diabetic groups (induced by Streptozotocin, STZ) and Rats in these two groups were further divided into 3, 7, 14, 30, 90 and 180 days-groups, including 5 rats respectively. The immunohistochemical studies of ICAM-1, VCAM-1 and CD45 were carried out in the retinal digest preparations or retinal paraffin sections, and the results were analyzed qualitatively, semi-quantitatively. Results: No positive reaction of VCAM-1 was found, and weak reactions of ICAM-1, CD45 were found in nondiabetic rats retina. The differ