To evaluate the effectiveness of ureteroscopic lithotripsy for the management of large proximal ureteral stones > 10mm using 14/16 Fr ureteral access sheath (UAS). Patients' data from prospective database undergoing ureteroscopic laser lithotripsy with a use of 14/16Fr UAS were collected. All patients were pre-stented prior to the procedure. The fragmentation was performed with a semi-rigid ureteroscope using holmium laser energy with a power setting of 35W (frequency-35Hz; energy-1J). Follow-up was scheduled at 4 weeks and 3 months postoperatively. In total 78 patients, 43 males and 35 females, were included in the study. The mean age of the patients was 59.5 ± 13.3 with a mean maximal stone diameter of 13.4 ± 2.1. The mean operative time was 35.7 ± 9.7 and the mean hospital stay was 2 ± 0.7days. The primary SFR at 4 weeks was 73 patients (93.6%), while all 78 patients (100%) were stone free at 3-month follow-up, 2 of the patients receiving additional treatment. In total, 8 (10.2%) patients experienced Grade II complications. Intraoperative ureteral lesions were observed in 41 (52.6%) cases. Out of them 31 patients (39.7%) developed Grade 1, 8 patients (10.3%) Grade 2 and only 3 patients (2.6%) Grade 3 lesions. The use of 14/16Fr ureteral access sheath on pre-stented patients was associated with successful outcomes. A high stone-free rate of 93.6% was achieved at 4-week follow-up. The procedure was not associated with increased rate of postoperative complications and intraoperative ureteral injury.