Objective — to make morphological and immunohistochemical examinations of incompetent uterine scars in the late periods after cesarean section in comparison with anamnestic and clinical laboratory data and to identify the role of connective tissue dysplasia. Subject and methods. Sixty-six patients who had turned to the Institute when planning a pregnancy were examined in late periods (from 1 to 10 years) after cesarean section. Out of them, there were 44 patients with a postcesarean incompetent uterine scar detected after a comprehensive examination (a study group) and 22 patients with a competent uterine scar (a control group). All the patients underwent a questionnaire survey and assessment of the external and visceral signs of dysembryogenesis in accordance with the first edition of the Russian Society of Cardiology guidelines, a complete clinical and laboratory examination with in-depth evaluation of the hemostatic system and thrombodynamics test, and pelvic ultrasonography (USG) according to the standard protocol, as well as a special USG that included hydrosonography with hysteroscopy, hysterosonography, and histological and immunohistochemical examinations. Results. USG and ultrasound hysterosonography were established to be of paramount importance in the diagnosis of an incompetent uterine scar in the late postcesarean period. The delayed complications in patients with a postcesarean incompetent uterine scar were infertility (18.2%), uterine scar endometriosis (12%), hypermenorrhea (15.9%), oligomenorrhea (18.2%), and endometrial hyperplastic processes (12%). The large number (48%) of patients with connective tissue dysplasia in the incompetent uterine scar group is attributable to the more unfavorable course of pregnancy and childbirth, which causes a higher rate of abdominal delivery. A morphological (including immunohistochemical) examination showed that the structural components of postcesarean incompetent uterine scars were identical in women with and without connective tissue dysplasia. They were characterized by persistent granulomatous inflammation even after a long time (up to 10 years) and by the presence of disorganized connective tissue areas as foci of a jelly-like homogeneous structure, which were devoid of collagen and fibrin. Conclusion. The large number of patients with connective tissue dysplasia in the incompetent uterine scar group is due to the more unfavorable course of pregnancy and labor and to the higher rate of cesarean section.