Transurethral Ureterolithotripsy (TUL) is a frequently used procedure in urology departments. Many urologists perform TUL without antibiotic prophylaxis; however the use of chemoprophylaxis before TUL remains a controversial issue in urology. This study was carried out to assess the safety of omitting antibiotic prophylaxis prior to TUL. In a prospective randomized clinical trial from January 2005 to December 2007, 114 patients with ureteral stones were enrolled; Fifty seven had preoperative antibiotic prophylaxis administered before TUL and fifty seven patients underwent TUL without antibiotic prophylaxis. The rate of postoperative infectious complications (fever, positive blood culture, significant bactriuria), the length of hospital stay and overall stone free rate were compared between the two groups. There was no statistically significant difference between two groups in the operation time, length of hospital stay, postoperative bacteriuria, positive urine culture, postoperative fever and overall success rate of TUL. It appears that the incidence of infectious complications does not increase in patients undergoing TUL without antibiotic prophylaxis if they have negative pre-operative urine culture and antiseptic technique have been performed thorough the procedure.