Abstract: AIM: To investigate the effects of angiotensin II (Ang II) on expression of acyl-coenzyme A: cholesterol acyltransferase-1 (ACAT-1) and peroxisome proliferator-activated receptor-γ (PPAR-γ) in macrophages and foam cells. METHODS: After human THP-1 cells were incubated with 160 nmol/L PMA for 48 h to differentiate into macrophages, the macrophages were cultured with 100 mg/L oxidized LDL for 24 h to differentiate into foam cells. Macrophages and foam cells were incubated with 1×10-6 mol/L Ang II for 48 h. ACAT-1 mRNA and PPAR-γ mRNA were detected by reverse transcription polymerase chain reaction (RT-PCR) and protein levels of ACAT-1 and PPAR-γ were measured by Western blot. RESULTS: ACAT-1 mRNA and protein levels were upregulated significantly (P<0.05) during differentiation from monocytes into macrophages and differentiation from macrophages into foam cells, with the PPAR-γ mRNA and protein levels significantly downregulated (P<0.05). When treated with Ang II, the ACAT-1 mRNA and protein levels of macrophages and foam cells were up-regulated more significantly (P<0.05, P<0.05) and their PPAR-γ mRNA and protein levels were more significantly downregulated (P<0.05, P<0.05). CONCULUSION: Ang II not only significantly promotes ACAT-1 expression but also inhibits PPAR-γ expression during the monocytes-macrophages differentiation.