For the treatment of AECB there are currently only four antibiotics available in the fluoroquinolone class: ciprofloxacin, gatifloxacin, levofloxacin, and moxifloxacin. In general, each of these four fluoroquinolones could be orally administered, and the bioavailability is good to excellent. All fluoroquinolones have high concentrations in the bronchial mucosa, in the epithelial lining fluid (ELF), as well as the alveolar macrophages. All have fast bactericidal action and provide optimal PD properties – area under the curve (AUC) to minimum inhibitory concentration (MIC) ratio, high concentration at the site of infection – which is reflected in the excellent clinical results in trials. Ciprofloxacin is the most active fluoroquinolone against P. aeruginosa, but it has low efficacy against S. pneumoniae. Therefore, this fluoroquinolone should primarily be used for P. aeruginosa infections. Moxifloxacin and gatifloxacin are more active against S. pneumoniae, but in clinical trials no differences could be demonstrated in comparison to levofloxacin. A once daily dosage is possible with gatifloxacin, levofloxacin, and moxifloxacin.