Objective — to determine the incidence of endometrium pathology in women with autoimmune thyroid pathology and history of reproductive losses, including an assessment of histological images and immunohistochemical (IHC) analysis of the endometrial receptor status. Material and methods. A prospective cohort study included a clinical and instrumental examination of 84 women aged 18 to 45 years with a history of 1 to 3 consecutive pregnancy losses. Patients were divided into 3 main groups: I — with primary hypothyroidism due to autoimmune thyroiditis (AITD) during drug treatment, II — euthyroid women with increased thyroid peroxidase antibody positive (TPOAb+) titers, III —without thyroid dysfunction. The control group — IV (n=21) consisted of women who have previously given birth and were planning pregnancy. To perform immunomorphological evaluation, we studied the results of endometrium biopsy, obtained using an aspiration curette (Pipelle) during the luteal phase of the menstrual cycle. As the second step, we used IHC analysis to evaluate the expression of steroid receptors (ERα, PR) in endometrial tissue. Results. The study of endometrium aspiration biopsy identified high incidence of endometrium pathology in the main groups. In group I, the frequency of luteal phase insufficiency (p=0.014) was statistically significant in the context of unchanged progesterone serum level. IHC analysis found reduced expression of ERα in the stromal epithelium and glands in groups I and II as compared to group III (p<0.05) and group IV (p<0.05). Reduced indicators of PR expression were identified in stroma and glands in group I in comparison to other groups (p<0.05). Conclusions. Morphological changes of the endometrium and impairment of its receptor apparatus in women with either primary hypothyroidism due to AITD or with increased titers TPOAb+ are a basis for considering this category of women high risk for an unfavorable outcome of pregnancy and for determining the appropriateness of their examination at the pregravid stage.