To evaluate the matrix metalloproteinase-1 (MMP-1) expression in different parts of pelvic connective tissue in postmenopausal women with and without pelvic organ prolapse (POP). Ninety-one samples were obtained from only postmenopausal women (42 with POP and 49 non-POP subjects). All women were evaluated by pelvic organ prolapse quantitation. The POP group had stage 2 or more, and the controls had stage 1 or less. Round ligament (RL) and uterosacral ligament (USL) biopsies were obtained from women with POP and controls. Immunohistochemistry for MMP-1 was performed on formalin-fixed and paraffin-embedded sections. The two groups were matched for age, body mass index, parity and postmenopausal status. MedCalc Statistical Software Programme Version 12.0.5 was used for statistical analysis. Expression of MMP-1 were significantly higher in both RL and USL tissue from postmenopausal women with POP, compared with controls. MMP-1 immunoreactivities were identified in both RL and USL biopsies from all women with and without POP. The expression pattern of MMP-1 were similar in these ligaments and were significantly higher in POP group compared with control subjects. These changes indicate a possible relation between MMP-1 expression of RL and USL in women with and without POP.