Ninety-six patients with chronic bacterial prostatitis (CBP) and evidence of infection were randomized to receive a 4-week oral course of either prulifloxacin (a new fluoroquinolone) 600 mg or levofloxacin 500 mg once daily. They were evaluated with the Meares-Stamey test and the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) at baseline and one week after therapy completion. Patients with microbiological eradication were evaluated again with the Meares-Stamey test 6 months after therapy completion. The microbiological eradication rate was 72.73% for prulifloxacin and 71.11% for levofloxacin (p=0.86) and the reduction in the NIH-CPSI was 10.75 and 10.73, respectively (p=0.98). Safety was comparable, with 18.18% adverse events for prulifloxacin and 22.22% for levofloxacin (p=0.79). Thus, a 4-week course of prulifloxacin 600 mg once daily is at least as effective and safe as levofloxacin 500 mg once daily in the treatment of CBP.