To investigate the effects of estrogen treatment on aortic endothelial senescence and atherosclerosis, an ovariectomized female rabbit model was constructed, and human umbilical vein endothelial cells were utilized to explore the potential mechanisms. Twenty-eight female rabbits were randomized into 4 groups (7 each): sham operation, ovariectomized, ovariectomized plus low-dose estradiol treatment, and ovariectomized plus high-dose estradiol treatment. All rabbits were fed on high-cholesterol diet for 12 weeks. Blood samples were collected to determine the serum estradiol, asymmetric dimethyl L-arginine (ADMA), and lipid levels, and the aortas were separated for histopathologic analysis. After ovariectomy and high-fat diet, the concentration of serum estradiols declined significantly (P < 0.01) and the levels of ADMA and serum lipids increased (all P < 0.01) as the area of senescent endothelium and atherosclerotic lesions enlarged (both P < 0.01). However, administration of estradiols reduced the levels of ADMA, total cholesterol, and low-density lipoprotein (LDL) cholesterol and inhibited endothelial senescence and atherosclerosis (all P < 0.01). Simultaneously, the concentration of high-density lipoprotein cholesterol and triglyceride increased (all P < 0.01). In vitro experiments also confirmed that estradiols could decrease the ADMA levels induced by oxidized LDL and inhibited oxidized LDL–induced and ADMA-induced human umbilical vein endothelial cell senescence. These results indicate that estrogens can inhibit endothelial senescence and atherosclerosis with reduced ADMA levels and improved lipid profile.