Abstract: Sixteen pyridonecarboxylic acids, characterized by having a chlorine atom and a cyclopropyl group at the 6- and 1-position respectively, substituted amino groups at the 7-position, and some substituted groups (chloro, nitro, amino, dimethylamino) at the 8-position, were synthesized. In vitro antibacterial activities of these compounds were tested. The fluoroquinolones ciprofloxacin and norfloxacin were included for comparative purposes. The results showed that both 11Ca and 11Cc were 4-8 times more active than ciprofloxacin and norfloxacin against S. aureus-15 in vitro, but with the same activity as ciprofloxacin against E. coli-22 and P.aeruginosa-29.