In our study we considered the possible interference of cefetamet-pivoxil with the intestinal microflora. We used 60 germ-free mice in which an intestinal microflora similar to the human one had been implanted. They were treated with 14.3 mg/Kg/die (standard dose) and a 28.6 mg/kg/die (daily dose) of cefetamet-pivoxil by oral route. The results obtained in vivo proved that cefetamet-pivoxil at therapeutic doses does not influence the normal intestinal microflora.