Cardiovascular disease, in spite of the significant interventions that have been made for primary and secondary preventions, is still the main cause of death in men and women in the western world. The prevalence of myocardial infarction in women with normal level of estrogens is very rare and 3-5 times lower than in men. However, this favorable relationship disappears in older women. Thus, the results from several clinical trials regarding the hormone status of women and the occurrence of cardiovascular events have led to the conclusions that estrogens exert a protective effect on atherogenesis, on formation of the atherosclerotic plaque, and, subsequently, on clinical manifestations of atherogenesis. In the last years, after the development of models for studying atherogenesis significant progress has been made, concerning the understanding of evolutionary biological and cellular events, leading to atherogenesis. In this review, atherogenesis (the formation of atherosclerotic plaque and its stages), the factors which advance atherogenesis (environmental and genetic), the effect of estrogens on the stages of atherogenesis, and the effect of estrogens on the factors which promote atherosclerosis will be discussed. Finally, hormone replacement therapy will be briefly described.