The rabbit which for practical reasons is so frequently used for experimental arteriosclerosis considerably differs from humans in its metabolism, nourishment, and arterial wall responses to atherogenic noxae. In this respect, domestic pigs show more resemblance to the conditions in man, and they have recently been used for experimental research work in the field of atherosclerosis. Our own investigations performed with a view to constructing an antherosclerosis model being as far as possible resemblant to conditions prevailing in humans have shown that among various forms of diets only one combined form which is rich in cholesterol (1.5 percent) and lipids (15 percent) produces changes in the intima that in certain arterial regions correspond to lesions found in humans. These are lipofibrous beds up to complicated atheromas. The location of the spontaneous changes (without atherogenic diet) suggest that these may be considered as early stages. The various forms of development were studied light- and electron-microscopically; moreover the development of the blood lipids was determined biochemically during the experiment.