The aim of this study was to determine the relationship of innervation in anterior vaginal epithelium with the etiology of stress urinary incontinence (SUI). Fifty-three biopsy specimens of the anterior vaginal epithelium were obtained from 53 subjects in control, pelvic organ prolapse (POP) and SUI groups. Routine HE staining and immunohistochemical staining for protein gene product 9.5 (PGP9.5) were performed for all specimens. PGP9.5 immunoreactivity was identified in nerve fibers and cells of the epithelium and subepitheliual connective tissue of vagina. The nerve fiber profiles of vaginal epithelium in the SUI/POP groups were significantly lower than those in the control group (P < 0.05). There was no correlation between the nerve fiber profiles and parity in SUI, POP and control groups. Decrease of nerve fiber profiles in anterior vaginal epithelium might lead to the occurrence of SUI.