—In earlier studies, our group has established a new “immunological” hypothesis for atherogenesis supported by experimental and clinical studies showing that inflammatory immunological reactions against heat shock protein 60 initiate the development of atherosclerosis. In the present study, we describe the discovery of a so-far-unknown network of dendritic cells in the innermost layer of arteries, the intima, but not veins of healthy humans and rabbits. The number of these dendritic cells is comparable to that of Langerhans cells in the skin, and dendritic cells show a similar phenotype (CD1a⁺ S-100⁺ lag⁺ CD31⁻ CD83⁻ CD86⁻ and no staining for von Willebrand factor or smooth muscle cell myosin). These vascular-associated dendritic cells accumulate most densely in those arterial regions that are subjected to major hemodynamic stress by turbulent flow conditions and are known to be predisposed for the later development of atherosclerosis. These results open new perspectives for the activation of the immune system within the arterial wall.