Atherosclerosis is the leading cause of illness and death in Western societies. It is now clear that the disease is a result of a chronic fibroproliferative-inflammatory response of the arterial intima leading to the formation of atherosclerotic plaque. There is, however, strong experimental evidence for a "mutation theory of atherosclerosis," underlining the similarity between atherosclerotic and carcinogenic processes. This review provides an overview of the studies that support the role of genetic alterations in the disease. The demonstration of microsatellite instability and loss of heterozygosity in smooth muscle cells of human plaques suggests that genomic destabilization may play a pivotal role in atherosclerotic mechanisms. Furthermore, the use of accepted biomarkers of carcinogenic exposure-such as DNA adducts and cytogenetic end points-recently has provided evidence consistent with the view that somatic cell alterations are critical in atherogenic process. It follows that the study of DNA damage may provide new insights into the pathogenesis of atherosclerosis and lead to the development of novel therapeutic approaches.