The minimal inhibitory concentrations (MIC) and the minimal bactericidal concentrations (MBC) of xibornol against 100 strains of Staphylococcus aureus, clinically isolated, have been evaluated. Xibornol has shown very good in vitro activity and a significant uniformity of the results. In fact the inhibitory and bactericidal activity range was between 2 micrograms/ml and 8 micrograms/ml.