The presence of Listeria monocytogenes in feces of animals has been related with ingestion of contaminated foods. In the study reported here, healthy mice inoculated SC with L monocytogenes excreted the organism in their feces, regardless of whether they developed clinical signs of infection. Listeria monocytogenes was isolated simultaneously from liver, feces, and bile of inoculated mice, which strongly suggested that the microorganism reached the gastrointestinal tract by biliary excretion.