 The objective of this study was to detect the morphological symptoms of cirrus and endometrioid ovarian cancers with a low degree of differentiation. The results of morphological diagnostics of 100 patients of different ages suffering from ovarian cancer were analyzed. Specific histological and cellular features of cancer cells were identified in order to distinguish between poorly differentiated cirrus carcinoma and endometrioid ovarian cancer with reduced differentiation. This allowed for a more accurate diagnosis based on the analysis of the operating material, which could be used to draw up a treatment plan and determine the prognosis of the disease. Macro and microscopic examinations of the operating material should also be conducted using traditional staining techniques, as well as with the use of immunohistochemistry. This article was authored by N. M. Kmonitsky, Z. Y. U. Maliva, V. A. Lipova, and others.