Abstract: To discover a modified and more efficient route to transforme an antibacterial fluoroquinolone to an antitumor fluoroquinolone,carbonylhydrazone was used as an isostere of C-3 carboxylic group of norfloxacin ( 1 ).Ten title compounds,1-ethyl-6-fluoro-7-piperazin-1-yl-3-(substituted)benzylidene hydrazinocarbonyl-quinolin-4(1H) ones 3a-3j were designed and synthesized.The structures of the synthesized compounds were confirmed by elemental analysis and spectral data,their in vitro antitumor activities against CHO,HL-60 and antibacterial and L1210 activity were evaluated.Preliminary results of pharmacological tests revealed that the title compounds showed more significant cytotoxic activity and poorer antibacterial activity than those of the parent norfloxacin.