Objective: to investigate the morphological features of the extraplacental membranes (EPM) of the placentas obtained from women with undifferentiated connective tissue dystrophy (UCTD) and premature rupture of the fetal membranes (PROFM). Material and methods. EPMs of 65 placentas, including 55 from study group women and 10 from control women (having no manifestations of UCTD and PROFM), underwent morphological examination (visual examination, histological and immunohistochemical studies, and electron microscopy). Results. There was subamniotic edema, disorientation and fragmentation of collagen structures in the compact layer, a structural change in the brush border of the amniotic epithelium, and a predominance of vacuolated cytotrophoblast forms in the structure of EPM of the placentas from of women with UCTD. Structural changes were accompanied by the altered function of EPM cells and identified by immunohistochemistry as higher MMP-9 expression by amniocytes and cytotrophoblast cells. PROFM was typified by the proliferation of amniotic epithelium; by the ordered arrangement of collagen fibers, and by large, longitudinally oriented fibroblasts. The structural changes in UCTD and PROFM were also accompanied by the altered function in the EPM cells as higher MMP-9 expression in amniocytes and cytotrophoblast cells. The latter was accompanied by the enhanced proteolysis of the extracellular matrix and can serve as one of the mechanisms, which triggers PROFM. Conclusion. Impaired histoarchitectonics and higher MMP-9 expression in the EPM cells should be considered as a manifestation of connective tissue disorganization and may be considered as one of the components in the pathogenesis of PROFM in the presence of UCTD.