Ovaries removed at 1,050 autopsies (accidental deaths) and from 300 patients with various benign gynaecological diseases were studied in search of the incipient benign epithelial tumors. One percent of the ovaries contained incipient mucinous tumors, 1.1% -Brenner tumors, 0.5% - endometrioid tumors. The exact percentage of the serous tumors was difficult to establish because of the absence of morphological criteria that distinguish these tumors from tumor-like conditions (inclusion cysts). The mucinous and Brenner tumors, as well as some serous tumors were located deep in the medullary or hilar regions of the ovary and were not con­nected to the covering of the ovary. The theory of incessant ovulation that links ovulatory damage of the ovarian surface with the initiation of neoplastic growth does not explain the genesis of all epithelial tumors. It is more likely that the latter two types arise in other parts of the female gonad. The process of morphogenesis of epithelial benign tumors is closely related to stromal altera­tions, specific for each histogenetic entity.