Mid-urethral slings (MUS) now represent a gold standard in the treatment of female stress urinary incontinence (SUI). Second generation trans-obturator slings (TOT) have proven to be as effective as retropubic tension-free vaginal tape (TVT) with fewer major complications. A third generation of the MUS inserted through a single vaginal incision (SIS) has become a means to overcome significant post-operative groin pain. Novel types of SIS with a more robust and adjustable anchoring mechanism can assure adequate long-lasting attachment to the obturator membrane (OM). Objective of this study was to compare an inside-out TOT with an innovative fixation SIS in randomized controlled trial on patients undergoing their primary surgery for urodynamic SUI.