Aim To investigate the effect of angiotesinⅡ(AngⅡ) on the expression of niemann-pick protein C1(NPC1) in THP-1 macrophages,and also explore the effect on the rate of cholesterol effluent. Methods Macrophages were converted from THP-1 monocytes induced by phorbol 12-myristate 13-acetate(PMA) for 48 h,and then they were treated by AngⅡ at different concentrations.The expression of NPC1 mRNA and protein was determined by reverse transcription-polymerase chain reaction(RT-PCR)and Western Blotting respectively. Cholesterol effluent was measured by liquid scintillator. Results Compared with the control group,the expression of NPC1 mRNA and protein were significantly downregulated when incubated with Ang Ⅱ dose-dependently.Meanwhile,the effluent rate of cholesterol was also decreased. Conclusion Angiotesin Ⅱmay inhibit the expression of NPC1 in THP-1 macrophages and decrease the effluent rate of cholesterol,contributing to the development of atherosclerosis.