We report in this work the antibacterial evaluation of 12 lipophilic fluoroquinolone derivatives containing diaminoalkyl side chains at C-7 position. The compounds were investigated against 15 bacterial strains including gram-negative and gram-positive species of clinical and microbiological importance. Three compounds (5, 10 and 11) were as active as or more efficient than gatifloxacin against gram-positive bacteria M. lentus. When compared with gatifloxacin compound 10 was 16 times more active. Two compounds (11 and 12) were twice more active than the reference compound against S. aureus.