Norfloxacin is an oral fluoroquinolone antimicrobial agent recently released for the treatment of uncomplicated and complicated urinary tract infections. The drug antagonizes DNA gyrase, an enzyme essential for bacterial DNA replication. Norfloxacin is more potent and broader in spectrum than the earlier developed analogue, nalidixic acid, and is active in vitro against virtually all bacterial pathogens causing urinary tract and gastrointestinal infections, aerobic gram-negative bacilli causing sepsis in neutropenic patients, and Neisseria gonorrhoeae. The drug is administered orally twice daily and achieves high concentrations in urine, stool, renal tissue, and bile. Norfloxacin was at least as effective as currently used agents in treating urinary tract infections, and, in limited studies, bacterial gastroenteritis, gonorrhea, bacterial prostatitis, and prevention of gram-negative bacillary infection in neutropenic patients. Adverse drug effects were mild and included disturbances of the gastrointestinal tract and the central nervous system. Norfloxacin shows promise as an antibacterial agent for genitourinary and gastrointestinal infections.