The purpose of this study was to determine if sacral colpopexy has an impact on in vivo vaginal biomechanical properties. Thirty-five participants who underwent sacral colpopexy were enrolled in this prospective clinical trial. In vivo vaginal biomechanical properties, including elasticity, viscoelasticity, and vaginal stiffness index, as well as symptom severity questionnaires (pelvic floor distress inventory-short form) and Pelvic Organ Prolapse Quantification (POP-Q) examination, were performed preoperatively and 6 weeks postoperatively. Thirty-two participants completed the study. Six weeks after sacral colpopexy participants demonstrated a decrease in prolapse related symptoms (POPDI-6 score, 39.8 vs 9.0, P < .00001) and 97% demonstrated anatomical cure of their prolapse. At 6 weeks follow-up participants demonstrated an increase in elasticity (2.26 vs 3.43, P < .00001), viscoelasticity (1.55 vs 4.08, P < .000001), and vaginal stiffness index (108.65 vs 164.50, P < .01). These findings suggest that sacral colpopexy increases in vivo vaginal biomechanical properties, as well as decreasing anatomical and symptom-related severity of pelvic organ prolapse.