The distribution of estrogen receptors in the ovaries of postmenopausal women is a very up-to-date subject in the aspect of advantages and complications of estrogen replacement therapy and the risk of estrogen-dependent neoplasms of reproductive organs. Both ovarian structure and immunolocalization of estrogen receptor alpha (ERalpha) in postmenopausal women are substantially different than they are in women at the reproductive-age. The most important changes in the ovarian structure after menopause include a blurring of the line between medulla and cortex, the reduction of cortex thickness, formation of epithelial inclusion cysts, reduction of follicle number, tendency to fragmentation of corpora albicantia, and stromal invaginations of the surface epithelium. In the ovaries of reproductive-age women, ERalpha is observed in stroma, in protective, granular and interstitial cells as well as corpus luteum lutein cells. After menopause it is found in the cells of stroma, inclusion cysts and the ovarian surface epithelium (OSE). Particularly vital change in the structure of postmenopausal women's ovaries in the aspect of the development of estrogen-dependent neoplasms is associated with the occurrence of epithelial inclusion cysts and the presence of ERalpha in their epithelium. 90% of ovarian epithelial neoplasms, and especially serous cancers, are known to develop from epithelial cysts and (or) in OSE. On the other hand, finding ERalpha in the ovarian stroma and in luteal and paraluteal cells of the corpus luteum, especially in perimenopausal women, proves the auto- and (or) paracrine regulation of these cells; it is also an evidence for steroidogenic activity in the ovary.