Oligella urethralis is an organism which is normally isolated as a commensal from the genitourinary tract. We describe the first two reported cases of CAPD-associated peritonitis caused by this organism. Both isolates were found to be resistant to ciprofloxacin, while relatively sensitive to a wide range of antimicrobial drugs. These findings indicate that this organism may be an opportunistic pathogen for CAPD patients, and that extensive ciprofloxacin usage provides a selection pressure for emergence of resistance.