A benign disease, endometriosis has characteristics of cancer, such as cell invasion, uncontrolled growth, stimulation of neo-angiogenesis, resistance to apoptosis, chronic inflammation, and the ability to metastasize. According to various specialists, malignancy is observed in 0.6—11.4% of patients with the genital form of endometriosis; 21.3% of cases of endometriosis-associated cancer have extra-ovary localization. Among them, 78% of patients have tumors in the colorectal intestinal tract (so-called endometriosis-associated intestinal tumors, EAITs). The literature describes about 50 clinical observations of endometriosis-associated intestinal tumors. These tumors can clinically manifest themselves as primary malignant intestinal tumors. In such cases, the data from immunohistochemical analyses of tumor biopsies (cytokeratin — CK7, CK20; marker antigens CDX2, CD10; estrogen and progesterone receptors — ER and PR) can play a significant role in making the correct diagnosis. The article presents 3 clinical observations of endometrial carcinomas found in retrocervical endometrial infiltrates.