A series of (-)-9-fluoro-2,3-dihydro-3(S)-methyl-10-(4-substituted-1-piperazinyl)-7-oxo-7H-pyrido [1,2,3-de] [1,4]-benzoxazine-6-carboxylic acid (5-8) was synthesized and evaluated for antibacterial activity against gram(+) and gram(-) bacteria. These synthesized compounds showed a lower activity than levofloxacin.