Aim To investigate the effects of scavenger receptor class B type Ⅰ(SR-BⅠ) in atherosclerosis by observing the change of SR-BⅠ expression. Methods Eighty patients with hypercholesterolemia and sixty healthy persons were investigated as hyperlipidemia group and control group respectively.Blood samples were extracted from ulnar vein.Blood serum,plasma and platelets were extracted and stored at a refrigerator of-80℃.The level of angiotensin Ⅱ(AngⅡ) in plasma and nitric oxide(NO) in serum were detected by the method of radioimmunity and nitrate reductase respectively.The expression of SR-BⅠ mRNA and protein on platelet were assessed by real-time polymerase chain reaction(RT-PCR) and Western Blotting respectively. Results The plasma AngⅡ and serum NO of hyperlipidemia group were higher than that of control group(P<0.01).The expression of SR-BⅠ mRNA and protein on platelets were lower in hyperlipidemia group than those of control group(P<0.05 and 0.01).The expression of SR-BⅠ protein was inversely correlated with the plasma AngⅡ(r=-0.488,P<0.05) in patients with hypercholesterolemia. Conclusion The expression of SR-BⅠ decreases and the decrease of SR-BⅠis related to AngⅡ.