Objective: To investigate the effect of preoperative tamsulosin use on the success and complications rates of ureteroscopy for ureteral stone removal. Study Design: A randomised clinical trial. Place and Duration of Study: Department of Urology, Dursun Odabas Medical Center, Van Yuzuncu Yil University, Turkey, from December 2020 to June 2021. Methodology: Patients were scheduled for ureteroscopy due to ureteral stones, and were randomly divided into two groups; 67 patients preoperatively were given 0.4 mg tamsulosin for 7 days and 70 patients were not given tamsulosin. Each patient's intraoperative surgical complications, preoperative and postoperative pain, postoperative fever, need for analgesia, stone-free rate, and double J ureteral stent (DJ) insertion rates were recorded and evaluated. Results: A total of 137 patients, 103 (75.1%) males, and 34 (24.8%) females, were included. In 70 (51.1%) of these patients, the stone was on the right side, while in 67 (48.9%) the stone was on the left side. The stone was in the distal ureter in 47 (34.3%) patients, in the middle in 38 (27.7%) patients, and the proximal in 52 (37.9%) patients. The patients who were given tamsulosin had lower preoperative visual analog scale (p=0.02), operation time (p=0.003), post-ureteroscopic lesion scale (p=0.01), postoperative 24th-hour visual analog scale (p=0.03), fever (p=0.02), and analgesic need (p=0.04), while their rate of accessing the stone (p=0.02); and their stone-free rates (p=0.02) was higher. Conclusion: Preoperative tamsulosin use increases the success of the operation and reduces complications.