Atherosclerosis is the primary cause of acute myocardial infarction and stroke. It is well established that arterial inflammation in response to accumulation and oxidation of lipoproteins in the vascular wall is the major factor responsible for the development of atherosclerosis. During recent years, it has become apparent that this vascular inflammation is modulated by a complex array of autoimmune responses against modified self-antigens in the atherosclerotic plaque and that both protective and pathogenic immune responses become activated as part of the disease process. Studies of hypercholesterolemia-induced immune activation in mouse models of atherosclerosis have demonstrated that Th1 cells contribute to disease progression while regulatory T cells are protective. It has been suggested that antigen presentation of modified self-antigens in the inflammatory environment of atherosclerotic plaques favors generation of antigen-specific Th1 cells over that of regulatory T cells, resulting in a local loss of tolerance. This concept has stimulated the development of plaque-antigen tolerogenic vaccines to dampen plaque inflammation and disease progression. A first generation of atherosclerosis vaccines based on peptides derived from apoB100 and heat shock proteins have demonstrated promising results in animal studies and are now approaching clinical testing.