The abusive and inappropriate use of antibiotics in digestive surgery has led to the selection of multi-resistant strains responsible for sometimes dramatic infective complications. The study of the normal digestive flora under pathological conditions, knowledge of the mechanisms of resistance, led us to propose the use of antibiotics with circumspection, depending on the germ isolated and the probable efficacy of the drugs. Prophylactic antibiotic therapy is only justified with regard to gram positive anaerobic bacteria or, in exceptional cases, where the risk seems high and may irremediably compromise the surgical procedure. Curative antibiotic therapy, after treatment of the infective focus, is often sufficient but depends on the bacteria: Whether anaerobic, staphylococci of Gram negative bacilli, with regard to which one should use narrow spectrum single antibiotics.