The fluorination of piperazinyl substituted quinolones has led to an interesting development of a series of new broad spectrum antibacterial agents that may be administered orally as well as parenterally and are well tolerated. Norfloxacin was an early compound, later followed by ciprofloxacin, enoxacin, ofloxacin and pefloxacin. In this overview the emphasis will be on the most extensively studied compound including comparisons, where data are available, with norfloxacin and ofloxacin. Enoxacin and pefloxacin will be omitted due to their pattern of side effects, which at present curtail their therapeutic use. More recent substances such as fleroxacin and defloxacin have not been sufficiently investigated to be considered in this context.