Aim To investigate the effects of early estrogen replacement therapy(ERT)of different doses on atherosclerotic lesions,serum lipid and monocyte chemoattractant protein-1(MCP-1)levels in ovariectomized fat-fed female rabbits.Methods Twenty-eight female New Zealand White rabbits were randomly divided into sham operation group,ovariectomized group,ovariectomized with low-dose ERT group(estradiol benzoate 200 μg)and ovariectomized with high-dose ERT(estradiol benzoate 1 mg)group.All rabbits were given high-fat diets after the surgery for 12 weeks.The levels of serum total cholesterol(TC),low density lipoprotein cholesterol(LDLC),high density lipoprotein cholesterol(HDLC),estradiol and MCP-1 were measured.12 weeks later,the aortas were taken for pathological analysis and for calculating the areas of atherosclerotic plaques.Results Compared with sham operation group,the serums levels of TC,LDLC and MCP-1 in ovariectomized group were significantly increased after high-fat diet for 12 weeks,meanwhile the serum levels of HDLC and estradiol were decreased.But the above indexs had no differences between ERT groups and sham operation group.Compared with low-dose ERT group,high-dose ERT group had higher levels of estradiol and lower levels of MCP-1.After high-fat diet for 12 weeks,the extent of atherosclerotic lesions of aorta in ovariectomized group was remarkably bigger than that in sham operation group.The extent in both ERT groups was significantly smaller than that in sham operation group and ovariectomized group.There were no statistical difference in the aortic lesions among two ERT groups.The areas of atherosclerotic plaque were positively correlated with the serum levels of LDLC,TC,and MCP-1,but negatively correlated with the serum levels of HDLC and estradiol.Conclusions Early ERT can modulate the blood lipid,decrease the serum levels of MCP-1 and reduce the areas of atherosclerotic plaque.The antiatherogenic effect of early ERT may be associated with its effects of ameliorating the lipid metabolism and anti-inflammation.