Aim: To evaluate the risk of bacteriuria after transurethral resection of the prostate and the preventive effects of different kinds of antibiotics. Patients and Methods: Urine was collected for culturing 1 week before the operation and on postoperative days 2 and 10. The patients were divided into four groups: group 1 patients were given a first- generation cephalosporin (cefazolin 1 g), group 2 patients received a second- generation cephalosporin (cefuroxime 750 mg), group 3 patients were given a third- generation cephalosporin (ceftazidime 1 g), and group 4 patients received a placebo. Results: The 2nd-day postoperative bacteriuria rates were similar in all groups. On the 10th day, the incidence rates of bacteriuria in group 4 and group 1 patients were 40 and 31%, respectively (p = 0.661). In group 2, the bacteriuria incidence rate was 6.6%, and when compared with the placebo group, the difference was considered significant (p = 0.002). The difference between group 3 and group 4 was also significant (p = 0.003). There were statistically significant differences between group 1 and group 2 (p = 0.008) and between group 1 and group 3 (p = 0.01). Conclusions: Our study demonstrated that postoperative bacteriuria incidence rates are high, even in patients who underwent transurethral resection of the prostate with sterile urine, but it can be reduced by using antibiotic prophylaxis with cefuroxime or ceftazidime.