To compare the outcomes of using Ultrathin semirigid retrograde ureteroscopy and antegrade flexible ureteroscopy to treat proximal ureteric stones of sizes 1-2cm. A prospective randomized multicenter study included patients who had proximal ureteric stones 1-2cm, amenable for ureteroscopy and laser lithotripsy between August 2023 and February 2024. Two hundred thirty patients were divided evenly into two treatment groups. Group I included patients treated with antegrade flexible ureteroscopy and holmium laser stone fragmentation, and Group II included patients treated with retrograde ultrathin semirigid ureteroscopy. The study groups were compared in terms of patient demographics, stone access success, operation time, reoperation rates, peri-operative complications, and stone-free status. Group I included 114 patients, while Group II included 111. The mean age of the patients was 33.92 ± 10.37years, and the size of the stones was 15.88 ± 3mm. The study groups had comparable demographics and stone characteristics. The mean operative time was significantly longer in group I than in group II (102.55 ± 72.46min vs. 60.98 ± 14.84min, respectively, P < 0.001). Most reported complications were MCCS grades I and II, with no significant difference between the study groups. The stone-free rate after four weeks was 92.1% and 81.1% for groups I and II, respectively, which increased to 94.7% and 85.6% after eight weeks (P > 0.05). Antegrade flexible ureteroscopy is equivalent to retrograde ultrathin semirigid ureteroscopy in treating proximal ureteric stones regarding stone-free status and procedure-related morbidity. However, the antegrade approach has a longer operative time, greater fluoroscopy exposure, and longer hospital stays.