Aim To eluciadate the genesis of atherosclerosis by investigating the level of angiotensinⅡ(AngⅡ),the expression of scavenger receptor class B type Ⅰ(SR-BⅠ),angiotensinⅡ receptors type 1(AT1),type 2(AT2) and the relationships among them. Methods Eighteen rats were randomly divided into two groups as control group and atherosclerosis group.Atherosclerosis group were given high cholesterol feeds,vitamin D3 and aorta balloon injury.At the end of 12 weeks,HE and Masson stain were used to detect the structure of aorta wall and atherosclerotic plaque.The concentration of AngⅡ was detected by the method of radio-immunity.The protein expression of SR-BⅠ,AT1 and AT2 were investigated by Western Blot and immunohistochemistry,while their mRNA expression were measured by real time reverse transcription polymerse chain reaction(RT-PCR).The correlation between variances were analyzed by linear regression analysis. Results In atherosclerosis group,some endothelial cells were lost and the intima thicked.The smooth muscle cell(SMC) proliferated and lined up in disorder.The smooth muscles in the media were atrophic slightly.The structures and arrangements of elastic fibers were in disorder and the fibrous tissues proliferated.There were some hyperplasy in the aortic wall and formed atherosclerotic plaques contained with hyperplastic fibers.All of these were observed by HE and Masson stain.The level of AngⅡ in atherosclerosis group was higher than that in control group(210.80±31.56 ng/L vs 121.26 ± 25.32 ng/L,P<0.01).Compared with control group,the protein expression of SR-BⅠ,AT1 and AT2 increased significantly in atherosclerosis group(0.83±0.19 vs 0.16±0.03,P<0.01;1.02±0.12 vs 0.48±0.11,P<0.01;0.97±0.24 vs 0.13±0.03,P<0.01),and expressed mainly in cell membrane and cytoplasma.The aorta mRNA expression of SR-BⅠ,AT1 and AT2 increased significantly in atherosclerosis group than that in control group(0.76±0.17 vs 0.16±0.04,P<0.01;0.83±0.20 vs 0.33±0.08,P<0.01;0.78±0.13 vs 0.12±0.03,P<0.01).The protein expression of SR-BⅠ was directly related to the level of AngⅡ and the expression of AT1(r=0.717,P<0.05 and r=0.711,P<0.05). Conclusion The expression of aortic SR-BⅠ,AT1 and AT2 increase significantly in atherosclerotic rats,furthermore the increased expression of SR-BⅠ is related to the elevation of AngⅡ and activation of AT1.