The main indication for the use of hormone therapy is to control symptoms during the years around menopause. However, and because estrogens have receptors spread over many systems in the body, the use of hormones may have consequences on health. Hormone therapy consists of estrogens essentially, since menopausal symptoms mainly derive from estrogen deprivation at different target tissues. Progesterone has a neutralizing effect over endometrial proliferation, this being the reason for adding progestogens to hormone therapy formulations. Because of that, the impact of hormone therapy on health should also consider the specific effects of both estrogens and progestogens in addition to those of only estrogens. While this has turned to be of minor importance in some areas, it is not so in others, for example, the breast. This chapter analyzes the effect of estrogens, with or without progestogens, on tissues of interest for health. The analysis includes the central nervous system, the cardiovascular tree, the joints, the breast, and the genital organs, uterus, and ovary.