The paper presents the results of a study on the antagonistic activity of L. acidophilus DSM 20079 and DSM 20242 strains towards H. pylori, E. coli, and S. enteritidis strains isolated from patients. The largest zones of inhibited growth were found in all the H. pylori strains analyzed; those zones were larger than 20 mm. The L. acidophilus strains also inhibited the development of all the S. enteritidis strains and the size of the inhibition zones was larger than 12 mm. Amidst the E. coli strains, there were some strains that grew uninhibited by the selected L. acidophilus strains analyzed. The size of inhibited growth zones of other E. coli strains was between 11 and 16 mm.