Abstract: To discover novel antibacterial and antitumor lead compounds derived from fluoroquinolone carboxylic acids, aryl hydrazone moiety as an isosteric replacement of the C-7 piperazine group of ciprofloxacin, fifteen new 1-cyclopropyl-6-fluoro-7-arylidenehydrazino-quinolin-4(1H)-one-3-carboxylic acids( 4a - 4o )as title compounds were designed and synthesized, respectively. The structures were characterized by elemental analysis and spectral data. The in vitro antibacterial assay of the title compounds against S. aureus and E. coli bacterial strains exhibited poorer activity than parent ciprofloxacin, however, the results of antitumor activity against SMMC-7721, L1210 and HL60 cell lines demonstrated stronger inhibitory activity than parent ciprofloxacin, especially compounds with electron-withdrawing aryl groups were comparable to doxorubicin. It suggests that it is favorable for an improvement of antitumor activity to introduce a functional arylhydrazone group instead of piperazine ring into the 7-position of fluoroquinolone skeleton.