New quinolone derivatives bearing a cis- or trans-cyclohexane side chain at the C-7 position have been synthesized and evaluated for their antibacterialactivities against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa using the agar dilution method. The activities of compound 53 against these three bacteria were superior to those of the reference drug lomefloxacin. Compounds bearing