Study of 52 patients with ovarian endometriosis supports the point of view about the relative autonomy of ovarian endometriosis from the cyclic hormonal alterations in female organism. In the foci of endometriosis the signs of differentiation of the epithelium by both tubal and endocervical types are revealed. This enables one to admit the possibility of ovarian serous and mucinous carcinoma development from the foci of endometriosis. Marked dysplastic changes, up to the focal carcinoma, are revealed but there were no signs of invasion. In the genesis of endometrioid carcinoma the great importance is attributed to the step-like process: endometriosis----borderline endometrioid tumour----endometrioid cancer.
