We previously demonstrated the safety and efficacy of fluoroquinolone-macrolide combination therapy in category Ⅱ chronic bacterial prostatitis (CBP).The aim of this study is to retrospectively compare the microbiological and clinical findings of two treatment schemes for CBP based on the combination of azithromycin (500 mg,thrice-weekly) with a once-daily 500-or 750-mg dose of ciprofloxacin (Cipro-500 or Cipro-750 cohort,respectively).Combined administration of azithromycin (1500 mg week-1) with ciprofloxacin at the rate of 750 mg day-1 for 4 weeks rather than at 500 mg day-1 for 6 weeks increased the eradication rates from 62.35％ to 77.32％ and the total bacteriological success from 71.76％ to 85.57％.A significant decrease in pain and voiding signs/symptoms and a significant reduction in inflammatory leukocyte counts and serum prostate-specific antigen (PSA) were sustained throughout an 18-month follow-up period in both groups.Ejaculatory pain,haemospermia and premature ejaculation were significantly attenuated on microbiological eradication in both groups,but the latter subsided more promptly in the Cipro-750 cohort.In total,59 Cipro-750 patients showed mild-to-severn erectile dysfunction (ED) at baseline,while 22 patients had no ED on microbiological eradication and throughout the follow-up period.In conclusion fluoroquinolone-macrolide therapy resulted in pathogen eradication and CBP symptom attenuation,including pain,voiding disturbances and sexual dysfunction.A once-daily 750-mg dose of ciprofloxacin for 4 weeks showed enhanced eradication rates and lower inflammatory white blood cell counts compared to the 500-mg dose for 6 weeks.Our results are open to further prospective validation.