159 women with previous miscarriages were investigated and in 105 of them (66%) chronic endometritis was revealed. The immunohistochemical method with monoclonal antibodies to NK cells (CD16+, CD56+), HLA-DR+ and B-lymphocytes (CD20+) was used for diagnosis of chronic endometritis. More than a half of patients had chronic endometritis with autoimmune component (AIC) leading to the increase of antiendometrial antibodies (AEA) concentration in peripheral blood. The patients with chronic endometritis and AIC had significantly delayed secretory transformation of endometrium despite of normal ovarian luteal activity. AEA could have independent influence on hormone-receptor interaction provoking thus morphologic and functional disorders of endometrium. Complex therapy of chronic endometritis led to elimination of AEA and normalization of secretory transformation of endometrium.