Six strains lactobacilli – L. reuteri (3), L. plantarum (2) and L. brevis (1), and five strains enterococci – E. faecalis (3) and E. faecium (2) were tested for their inhibitory activity against some enteropathogenic bacteria and their tolerance to unfavorable conditions of life in the upper alimentary tract. Two tested strains of lactobacilli and three strains of enterococci repressed most strongly the growth of enteropathogenes. All three strains of L. reuteri showed high percentage of survival after treatment with gastric juice and bile (from 66.45% to 88.66%). The strain of L. plantarum 113-3 survived 62.15% and all tested enterococci – over 75%. All tested strains of lactobacilli and enterococci except L. brevis 129-3 (25.41% surviving) could successfully pass through the stomach and duodenum and reach the small intestine and colon. They contribute the balance of intestinal microflora.