Summary. Aim: to evaluate the features of the expression of the cytokine TGF-β1 and the transcription factor Snail1 in endometrial tumor cells, depending on the degree of differentiation and the level of spread of the malignant process. Object and methods: surgical material samples of 54 patients with endometrioid carcinoma of the endometrium (ECE) with the I–II stage of the disease (median age 59 years), which were examined using: morphological, immunohistochemical and statistical methods. Results: significantly higher expression of cytokine TGF-β1 and transcription factor Snail1 was shown in low-differentiated endometrial carcinomas that invade deeply into the myometrium, compared to tumors of a high and moderate degree of differentiation with shallow invasion into the myometrium. In endometrial tumors with high Snail1 expression, a significant decrease in the expression of the epithelial cell marker E-cadherin and an increase in the expression of the mesenchymal marker vimentin were found. It was established that high mRNA expression of the TGFB1 and SNAI1 genes correlates with a decrease in the 5-year survival time of patients with ECE (GEPIA2 database). Conclusions: the results of the study suggest that, associated with the epithelial-mesenchymal transition, TGF-β1 and Snail1 modulate certain morphofunctional characteristics of malignant endometrial neoplasms and participate in the formation of the aggressiveness of this form of cancer. The obtained data indicate a high probability of using Snail1 and TGF-β1 as prognostic markers of the course of the disease in patients with this oncological pathology.