Aim To observe the effects of panax quinquefolius saponin on plaque content and the gene expressions of perilipin and scavenger receptor CD36 assosciated with lipid metabolism of ApoE-gene knockout mice and explore the effect of panax quinquefolius saponin on atherosclerotic plaque stability and its possible mechanism.Methods Thirty-three ApoE knockout mice had been fed with a high-fat diet for 13 weeks until the mature atherosclerotic plaques formed.Thereafter, they were randomized to three groups: control group,panax quinquefolius saponin group,simvastatin group(positive control group).Two drug-treated groups were treated with respective drug in clinical recommended doses for another 13 weeks accompancied by feeding high-fat diet.Then all the mice were sacrificed at the end of experiment,their blood was collected for determining the concentrations of blood lipids.The morphology and composition of atherosclerotic plaques in aortic roots were examined in tissue sections.Four sections were choosed and stained with Movat and HE stains respectively.The lipid core in plaque as well as the ratio of lipid to collagen content in plaque in each mouse were measured and counted.The gene expressions of perilipin and CD36 were determined by Real-time fluorescent quantitative PCR technology.Results After treated drugs for 13 weeks,panax quinquefolius saponin group significantly reduced the lipid core as well as the ratio of lipid to collagen content in and the concentration of HDL in serum was significantly increased(p< 0.01).The gene expression of perilipin and CD36 in aorta were significantly