Background: Transobturator slings are currently promoted for the treatment of stress urinary incontinence (SUI) after radical prostatectomy (RP), but data on outcome remain limited. Objective: To assess, at midterm, the efficacy and safety of the inside-out transobturator male sling for treating post-RP SUI and to determine factors associated with failure. Design, setting, and participants: Prospective one-center trial involving 173 consecutive patients without detrusor overactivity, treated between 2006 and 2011 for SUI following RP. Intervention: Placement of an inside-out transobturator sling. Measurements: Baseline and follow-up evaluations included uroflowmetry and continence and quality-of-life (QoL) questionnaires. Cure was defined as no pad use and improvement as a number of pads per day reduced by >= 50% and two or fewer pads. Complications were recorded, and factors associated with treatment failure were evaluated. Results and limitations: Preoperatively, 21%, 35%, and 44% of the patients were using two, three to five, and more than five pads per day, respectively. After a median followup of 24 mo (range: 12-60 mo), 49% were cured, 35% improved, and 16% not improved. QoL was enhanced (p < 0.001), and 72% of patients were moderately to completely satisfied with the procedure. Maximum flow rates were slightly reduced (p = 0.004); postvoid residual volumes were similar (p = 0.097). Complications were urinary retention after catheter removal (15%), perineal/scrotal hematoma (9%), pain lasting > 6 mo (3%), and sling infection (2%); all were managed conservatively. Severe SUI before sling surgery was not associated with a worse outcome, whereas obesity and a history of pelvic irradiation or bladder neck stenosis were independent risk factors of failure, with risk ratios of 7.9 (95% confidence interval [CI], 3.3-18.9), 3.3 (95% CI, 1.4-7.8), and 2.6 (95% CI, 1.1-6.5), respectively. Conclusions: The inside-out transobturator male sling is an efficient and safe treatment for post-RP SUI at midterm. Patients with prior pelvic irradiation may not be suitable candidates. (C) 2011 European Association of Urology. Published by Elsevier B. V. All rights reserved.