An in vitro kill kinetics study evaluated eradication of 18 human ocular Staphylococcus isolates by commercial formulations of gatifloxacin 0.3% (Zymar, Allergan) and moxifloxacin 0.5% (Vigamox, Alcon Laboratories). Gatifloxacin demonstrated superior activity, which may be attributed to the presence of benzalkonium chloride 0.005% in its formulation.