Purpose: To assess the 5-year efficacy of the inside-out transobturator tension-free vaginal tape (TVT-O) for the treatment of stress urinary incontinence (SUI) and to explore possible predictors for long-term failure. Methods: Sixty-five consecutive patients who underwent TVT-O were prospectively enrolled. Patients who required concomitant anterior or apical pelvic organ prolapse repair or both and those with urodynamic occult SUI were excluded. Postoperatively, patients were scheduled for evaluation at 1, 3, 6, and 12 months and annually thereafter. Surgical failure was defined as positive stress test, daily episodes of SUI, and negative global satisfaction. Preoperative and interim clinical and urodynamic predictors for long-term failure were analyzed from a computerized database. Results: Sixty-one patients (mean age at surgery 56.6±10.2 years) completed 5 years of follow-up. Of these, 11 (18%) patients were classified as surgical failure, 5 (8%) as improved, and 45 (74%) as cured. Any SUI (100% vs. 10%, p=0.001), daily SUI (100% vs. 0%, p=0.001), overactive bladder (OAB) (100% vs. 48%, p=0.001), and the use of antimuscarinic drugs (64% vs. 26%, p=0.03) were found to be significantly more common among failure cases. Preoperative detrusor overactivity (odds ratio [OR] 7.6, 95% confidence interval [CI] 1.7-32.9), interim 1-year OAB (OR 20.5, 95% CI 1.9-215.4), and interim 1-year SUI (OR 26.4, 95% CI 1.5-475.2) were found to be significant independent risk factors for long-term surgical failure. Conclusions: An 18% rate of surgical failure was observed 5 years after TVT-O. Larger studies with longer follow-up periods may facilitate the identification of risk factors for failure and, thus, enable better preoperative consultation.