Bacteria and phages may be exposed to acid conditions in the stomach and to bile in the intestine. Survival of three strains of Vibrio vulnificus and three strains of its phages was examined at 37 degrees C after exposure to simulated gastric fluid at pH 3 to 4 or to 0, 1, and 2% bile in broth or buffer. Mean D-values (decimal reduction times) at pH 4 and 3 were 3.3 and 1.3 min for V. vulnificus and 97.8 and 0.7 min for its phages. No V. vulnificus survivors were found at pH 2.0. There were few survival differences among strains of V. vulnificus or its phages. Numbers of V. vulnificus increased 1 log in tryptic soy broth containing 1 or 2% bile after 3 h. Numbers of V. vulnificus and its phages remained constant in phosphate-buffered saline regardless of bile concentrations up to 3 h. Those V. vulnificus bacteria and phages that survive stomach acidity may proliferate in the small intestine, since they are resistant to bile.