Hypercholesterolemia is a major risk factor for the development and progression of cardiovascular diseases including atherosclerosis. A major active ingredient, scutellarin, from the plant Erigeron breviscapus was investigated for its hypocholesterolemic and atheroscleroprotective effects (30 and 100 mg/kg/day, p. o.). The serum lipid profile (total cholesterol, triglycerides, high density lipoprotein cholesterol and low density lipoprotein cholesterol) was monitored and aortic functions in Sprague-Dawley rats fed with normal diet, atherogenic diet or atherogenic diet plus oral administration of either scutellarin or simvastatin (a positive control) were tested. It was found that scutellarin markedly attenuated the increased serum total cholesterol induced by atherogenic diet. It caused a significant reduction in the atherogenic index. In addition, scutellarin administration could significantly enhance acetylcholine-induced nitrate/nitrite production, increase the gene expression of endothelial nitric oxide synthase and improve acetylcholine-induced endothelium-dependent vasorelaxation in rat isolated aortas. These data revealed that scutellarin could reduce the atherogenic properties of dietary cholesterol in rats. However, whether scutellarin's atheroscleroprotective potential targets endothelial function directly or indirectly on its antioxidative activity remains to be determined. ; Author name used in this publication: De-Jian Guo ; Author name used in this publication: Huan-Le Cheng ; Author name used in this publication: Shi-Lin Chen ; Author name used in this publication: Jian-Hong Wu