Aim To investigate the effects of renin angiotensin system (RAS) in atherosclerosis by observing the change of angiotensinⅡ type 1 (AT1) receptor expression and the effects of statin on it. Methods Sixty patients with hypercholesterolemia and forty healthy persons were investigated as hyperlipidemia group (Hyperlipidemias) and control group (Controls) respectively. Blood samples of ulnar vein were extracted from Controls and Hyperlipidemias. Blood serum, plasma and platelet were extracted and stored at a refrigerator of -80℃. The level of plasma angiotensinⅡ was detected by the method of radioimmunity. While the expression of AT1 mRNA and protein on platelet were assessed by reverse transcription polymerse chain reaction (RT-PCR) and Western blot respectively. Results The plasma angiotensinⅡ of Hyperlipidemias was higher than that of Controls (92.13±25.27 vs 50.85±21.12, p<0.01). The expression of AT1 mRNA and protein on platelets were higher in Hyperlipidemia than those of Controls(0.93±0.22 vs 0.25±0.06, p<0.01 and 1.35±0.32 vs 0.42±0.10, p<0.01). The expression of AT1 protein was directly correlated with the plasma angiotensinⅡ (r=0.369, p<0.01). Conclusions The increase of AT1 mRNA and protein on platelets is related with plasma angiotensin Ⅱ in patients with hypercholesterolemia.