New Zealand white rabbits were divided at random into three groups which were, fed a normal chow (Control ) and a high-cholesterol diet (HCD), a high cholesterol diet suplemented with Larginine(HCD-Arg) for 4 or 8 weeks respectively. In the high-holesterol diet group (vs HCD-Arg group),scanning electron micrographs of rabbit aortic arteries stained with silver nitrate showed that endothelium cells had irregular sizes and lacked the typical alignment in the direction of blood flow. Permeability of endothelium cells of atherosclerotic plaques was increased in HCD group (vs HCD-Arg group). Meanwhile, L-arginine could partly inhibit the development of atherosclerotic plaques. These data suggest that hypercholesterolemia enhances the endothelium lesion ;this effect is affenuated by dietary L-arginine.