The introduction of suburethral sling was a breakthrough in the treatment of stress urinary incontinence in women. The method is highly effective. However, the mechanism of action of a sling and the reasons for surgical failures are not fully understood. Aim: The aim of the study was to assess the impact of sling-pubic symphysis distance on eliminating the symptoms of stress urinary incontinence and urethral funneling. Materials and methods: The analysis included 106 patients who reported 3 to 6 months after sling placement for a follow-up visit encompassing clinical examination and standard ultrasonography. We evaluated the position of sling in relation to the pubic symphysis, urethral length, as well as urethral funneling length and width. Results: Cure criteria were met by 91 patients. Elimination of urethral funneling was achieved in 76.9% (n = 70) of cured patients. Urethral funneling was still present, yet shorter by a mean of 10.2 mm (p = 0.02) than before surgery in the remaining cured patients. There was a 32.5% reduction in the mean relative length of urethral funneling (p = 0.002). No significant differences were found in the pre- and postoperative funneling width. The tapepubic symphysis distance was lower in cured women: 23.2 mm vs. 26.1 mm in failed women (p = 0.04). Similar observations were made for cured patients with persistent urethral funneling vs. failed patients (22.47 mm vs. 26.0 mm, p = 0.027). There were no differences between cured patients without urethral funneling and cured patients with persistent postoperative funneling (23.5 mm; 22.5 mm; p = 0.417). Conclusions: Tape position in relation to the pubic symphysis is important for the elimination of stress urinary incontinence. Sling location closer to the pubic symphysis reduces the length of urethral funneling, but has no effects on its width in cured patients with persistent postoperative funneling.