Temafloxacin hydrochloride [(+/-)-7-(3-methylpiperazin-1-yl)-6-fluoro-1-(2,4-difluorophenyl)- 1,4-dihydro- 4-oxoquinoline-3-carboxylic acid hydrochloride] is a potent member of the 4-pyridone-3-carboxylic acid class of antibacterial agents and is currently under clinical development as a broad-spectrum antimicrobial agent. It is a racemate having a chiral center at the C3 of the 7-piperazin-1-yl group. The two enantiomers were synthesized and tested for their antibacterial activities. Although no difference in in vitro antibacterial activities was observed, a minor difference in in vivo antibacterial activities was observed. However, they both exhibited similar pharmacological profiles.