The isolate E. faecium BDU7 showed acid tolerance and survived at pH value as low as 2.0 at least for 1 h but showed tolerance at pH values of 3–5. The gastric pH in healthy humans is about 2–2.5. This pH causes the destruction of most microorganisms ingested. Hence resistance to human gastric transit is an important selection criterion for probiotic bacteria. The resistance of the strains to high bile conditions was determined. The result showed 57.6 and 8.4% survival of E. faecium in 1 and 5% bile respectively. Resistance to bile is a prerequisite for colonization and metabolic activity of probiotic bacteria in the small intestine of the host. The physiological concentration of human bile is between 0.3% and 0.5%.