Objective: The most significant cause underlying pelvic organ prolapse is connective tissue abnormalities, which might be generalized rather than restricted to certain organs. This study was performed to determine whether lung function impairments were present in women with pelvic organ prolapse. Methods: This case-control study included 207 patients with pelvic organ prolapse and 207 age, height, and years postmenopausal, one-to-one matched controls. All subjects underwent lung function examination by spirometry. All subjects were postmenopausal without hormone replacement therapy, and without clinical signs or histories suggestive of disorders known to affect the pulmonary function. Results: There were significant decreases in the forced vital capacity and peak expiratory flow in the women with pelvic organ prolapse (P-value=0.049 and 0.019, respectively). Significant differences in mean forced vital capacity were found in patients with stage II-IV prolapse (P-value=0.047). There was a positive correlation between the forced vital capacity or peak expiratory flow and age at the time of the pelvic organ prolapse (P-value<0.001 and <0.001, respectively). Conclusion: Restrictive pulmonary impairment was aggravated in advanced stages of pelvic organ prolapse, and was worse if pelvic organ prolapse developed at a younger age.