Transport of serous pre-beta and beta-lipopropeins (beta-LP) labeled by C14 protein and by C14 lipid into the wall of the aorta was studied histoautoradiographically and biochemically. The aortas of healthy rabbits and rabbits wuth experimental atherosclerosis were perfused in vitro with a medium containing rabbit pre-beta and beta-LP during 6 hours. After perfusion the mark was identified histoautoradiographically in all layers of the aorta. The presence of gradient in distribution of the mark from the inner layers of the aortas towards the outward part of the media indicated that the process of infiltration of the wall of the LP vessel was caused by their penetration from the lumen of the aorta. Nonuniformity in distribution of LP penetrated into the atherosclerotic aorta was noted, which was considered in connection with the changes occurred in the connective tissue of the wall of the aorta in the process of atherogenesis. Results of both morphological and biochemical investigations confirm an increased permeability of the aorta wall for LP in atherosclerosis and also substantiate the assumption about penetration of pre-beta and beta-LP into the wall of the vessel as a whole particle.