Objective: To compare long term efficacy and safety of an innovative single incision sling (SIS) with the inside-out trans-obturator sling (TOT) in the treatment of female stress urinary incontinence (SUI). Design: randomized controlled trial. Setting: single tertiary referral urogynecology center. Population: women with pure urodynamic SUI. Methods: randomized to either an SIS or TOT and followed-up for four years. Main Outcome Measures: The primary outcomes were objective cures defined with a negative cough stress test and subjective cure reported via patient’s satisfaction scale. Secondary outcomes involved surgery complications including re-operations, postoperative de-novo urgency, and impact on patient quality of life. Results: The objective (86.4% vs. 83.1%; 95% CI 0.30-2.02; p=0.635) and subjective cure rates (83.3% vs. 80.0%; 95% CI 0.33-1.94; p=0.657) were similar with the SIS and TOT groups. Both procedures were associated with low complication rates. Repeated surgery rates owing to recurrent SUI were 7.6% in SIS and 6.3% in TOT groups, respectively. Overall mesh exposure rate was 2.3% for both groups. Incidence of de-novo urgency didn’t vary between TOT and SIS patients. Both groups registered a significant quality of life improvement. Conclusions: Following long term follow-up, anti-incontinence SIS surgery proved non-inferior to inside-out TOT procedure in terms of objective and subjective cure rates. Funding: supported by Czech Republic Ministry of Health, No. FNBr65269705 Keywords: Stress urinary incontinence; mid-urethral sling; single incision sling; efficacy; patient-reported outcomes; randomized controlled trial Clinical Trial Registration: ClinicalTrials.gov, NCT02506309