Introduction and hypothesis: Of women with symptomatic prolapse, 13–39% experience voiding dysfunction (VD). The aim of our observational cohort study was to determine the effect of prolapse surgery on voiding function. Methods: Retrospective analysis of 392 women who underwent surgery between May 2005 and August 2020. All had a standardized interview, POP-Q, uroflowmetry and 3D/4D transperineal ultrasound (TPUS) pre-and postoperatively. Primary outcome was change in VD symptoms. Secondary outcomes were changes in maximum urinary flow rate (MFR) centile and post-void residual urine (PVR). Explanatory measures were change in pelvic organ descent as seen on POP-Q and TPUS. Results: Of 392 women, 81 were excluded due to missing data, leaving 311. Mean age and BMI were 58 years and 30 kg/m2, respectively. Procedures performed included anterior repair (n = 187, 60.1%), posterior repair (n = 245, 78.8%), vaginal hysterectomy (n = 85, 27.3%), sacrospinous colpopexy (n = 170, 54.7%) and mid-urethral sling (MUS) (n = 192, 61.7%). Mean follow-up was 7 (1–61) months. Pre-operatively, 135 (43.3%) women reported symptoms of VD. Postoperatively, this decreased to 69 (22.2%) (p < 0.001), and of those, 32 (10.3%) reported de novo VD. The difference remained significant after excluding concomitant MUS surgery (n = 119, p < 0.001). Postoperatively, there was a significant decrease in mean PVR (n = 311, p < 0.001). After excluding concomitant MUS surgery, there was a significant increase in mean MFR centile (p = 0.046). Conclusions: Prolapse repair significantly reduces symptoms of VD and improves PVR and flowmetry. [ABSTRACT FROM AUTHOR]