Studies of ofloxacin pharmacokinetics and pathogen susceptibilities suggested that this new fluoroquinolone might be particularly well suited to the treatment of urinary tract infections and prostatitis. Compared with carbenicillin and trimethoprim/sulfamethoxazole in separate studies of complicated urinary tract infection, ofloxacin achieved a significantly higher rate (p = 0.048) of microbiologic cures and more clinical cures than carbenicillin, while essentially matching the efficacy of the trimethoprim/sulfamethoxazole combination. Most common organisms were Pseudomonas aeruginosa in the first study and Escherichia coli in the second. In preliminary data from the prostatitis study comparing ofloxacin 300 mg given twice daily with carbenicillin 764 mg given every six hours, microbiologic cure rates were 100 percent with both medications. However, clinical cure rates were significantly higher (p = 0.048) with ofloxacin. Throughout these trials, ofloxacin has shown excellent safety and tolerability, with a lower incidence of nausea and diarrhea than with carbenicillin, and less nausea and rash than with trimethoprim/sulfamethoxazole. In all treatment groups, clinically significant laboratory abnormalities were uncommon and unrelated to the medications. Overall, these studies indicate that in complicated urinary tract infection the efficacy of ofloxacin is comparable with that of trimethoprim/sulfamethoxazole and superior to that of carbenicillin. In chronic bacterial prostatitis, results to date suggest that ofloxacin may be more effective clinically and as effective microbiologically as carbenicillin.