Horáčková Š., Žaludová K., Plocková M. (2011): Stability of selected lactobacilli in the conditions simulating those in the gastrointestinal tract. Czech J. Food Sci., 29 (Special Issue): S30-S35.The cell survival in the digestive tract is one of the main criteria required for the probiotics. The aim of this study was to evaluate the stability of the selected lactobacilli (Lactobacillus acidophilus CCDM 151; L. casei CCDM 198; L. rhamnosus CCDM 150, and L. fermentum ST 68) in conditions simulating those in the gastrointestinal tract as compared to the commercial probiotic strain Lactobacillus casei LAFTI L-26. The growth of lactobacilli decreased both after 2 h and 4 h incubation in MRS media with increasing concentration of bile salt but all lactobacilli had the ability to adapt in the environment of bile salt. Great differences in viability were detected between the isolated cells in the stomach simulating conditions. L. casei LAFTI L-26 and L. acidophilus CCDM 151 were most stable, L. rhamnosus CCDM 150 did not survive under these conditions. Milk revealed a strong protective influence on the viability of all lactobacilli in the stomach simulating conditions. The conditions existing in the small intestine did not influence the cell viability. Differences in autoaggregation were also observed.