- Objectives To investigate the possible association of increased matrix metalloproteinases (MMPs)-1,-9 with pelvic organ prolapse (POP) and to evaluate whether inflammatory processes contribute to its development. Study design Forty women who underwent hysterectomy, 20 with POP grade 2 and above, and 20 without POP, participated in the study. Biopsies from the uterosacral ligaments and vaginal mucosa were obtained from each woman. Each biopsy was sectioned and stained for MMP-1 and MMP-9 by immunohistochemical methods and with hematoxylin and eosin (H&E). MMP-1,-9 expressions were evaluated on the immunostained slides. H&E stained sections were examined for possible inflammatory changes. Results A higher stromal (extra-cellular) expression of MMPs-1,-9 was found in POP cases compared with controls in vaginal biopsies (MMP-1: p = 0.004; MMP-9: p = 0.042) as well as in uterosacral ligament biopsies (MMP-1: p = 0.011; MMP-9: p = 0.015). Increased intracellular expression of both MMPs was also demonstrated in fibroblasts in biopsies of women with POP (p < 0.001 for all). Most of these differences persisted after controlling for age. The degree of inflammatory changes reflected by the number of lymphocytes, plasma cells and capillary-sized blood vessels per 10 high power fields, was similar in specimens obtained from women with and without POP. Conclusions The expression of MMPs-1,-9 appears to be increased in tissues from women with POP. This supports an association, although not a causal relation, between increased MMPs-1,-9 and POP. Inflammation does not seem to play an important role in the pathogenesis of POP.