Objective: To observe the effects of red yeast rice(RYR) on blood lipid levels, aortic atherosclerosis(AS), and plaque stability in apolipoprotein E gene knockout(Apo E-/-) mice. Methods: Twentyfour Apo E-/-mice were fed with a high-fat diet starting from 6 weeks of age. Mice were randomized into three groups(n = 8 in each group): model group(Apo E-/-group), RYR group(Apo E-/-+ RYR group), and simvastatin group(Apo E-/-+ simvastatin group). Eight 6-week-old C57BL/6 mice were assigned as the control group and fed with a basic diet. After 36 weeks, plasma lipids and inflammatory factors were measured. Aortic atherosclerotic lesions by microscope, scanning electron microscope and transmission electron microscope were observed. Plasma levels of interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α) were measured with enzymelinked immunosorbent assay. The level of high sensitivity C-reaction protein(Hs-CRP) was detected by the scattering immunoturbidimetric assay. Protein expression of matrix metalloproteinase-9(MMP-9) and nuclear factor κB(NF-κB) in aorta were tested by immunohistochemistry. Results: Compared with the model group, treatment with RYR significantly decreased the levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, lipoprotein(a), and apolipoprotein B100 in Apo E-/-mice(P<0.01). Compared with the model group, treatment with RYR decreased the levels of Hs-CRP, IL-6, and TNF-α(P<0.01). RYR also reduced the protein levels of NF-κB and MMP-9 of the aorta. Conclusions: RYR has the anti-atherosclerotic and stabilizing unstable plaque effects. The mechanism might be related to the inflammatory signaling pathways. Objective: To observe the effects of red yeast rice (RYR) on blood lipid levels, aortic atherosclerosis (AS), and plaque stability in apolipoprotein E gene knockout (Apo E - / -) mice. Methods: Twenty four Apo E - / - were fed with a high-fat diet starting from 6 weeks of age. Mice were randomized into three groups (n = 8 in each group): model group (Apo E - / - group), RYR group RYR group), and simvastatin group (Apo E - / - + simvastatin group). Eight 6-week-old C57BL / 6 mice were assigned as the control group and fed with a basic diet. After 36 weeks, plasma lipids and inflammatory factors Aortic atherosclerotic lesions by microscope, scanning electron microscope and transmission electron microscope were observed. Plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured with enzyme-linked immunosorbent assay. of high sensitivity C-reaction protein (Hs-CRP) was detected by the scattering immunoturbidimetric assay. Protein expression of ma Results: Compared with the model group, treatment with RYR significantly decreased the levels of total cholesterol, triglyceride, low-density lipoprotein Compared with the model group, treatment with RYR decreased the levels of Hs-CRP, IL-6, and TNF- [alpha] (P <0.01). RYR also reduced the protein levels of NF-κB and MMP-9 of the aorta. Conclusions: RYR has the anti-atherosclerotic and stabilizing unstable plaque effects. The mechanism might be related to the inflammatory signaling pathways.