Transobturator midurethral slings (TOT) have been shown to have less risk of vascular and visceral injury than tension-free midurethral slings. Routine cystoscopy has therefore not been felt to be necessary. A case of bladder perforation unrecognized at the time of TOT placement is presented. Findings at sling removal suggested that a clinically nonapparent paravaginal defect may have been instrumental in the injury. Consideration should be given to routine cystoscopy at the time of transobturator sling placement.