The development of interventions to reduce human foodborne pathogens in the gastrointestinal ( GI ) tract of chickens will be important for improving the microbial food safety of poultry. Saccharomyces -derived prebiotic refined functional carbohydrates ( RFC ), composed primarily of β-glucans, mannanoligosaccharides ( MOS ), and D-mannose have been demonstrated to reduce GI colonization of Salmonella and Campylobacter when administered to poultry. Although they are presumed to inhibit adhesion of pathogens to the GI epithelium, this functionality of RFC has not been well characterized. In this study, we investigated the effects of RFC and other prebiotics on the adhesion of Salmonella Typhimurium and Campylobacter jejuni to the LMH chicken epithelial cell line in vitro. The reduction of adherent pathogens was observed to be dose-dependent with C. jejuni being more sensitive than Salmonella to inhibition by RFC. Comparison of the primary constituent carbohydrates of RFC found D-mannose to inhibit both pathogens less effectively than β-glucan and MOS, suggesting that it contributes less to inhibition of pathogen adhesion than the other carbohydrates. Finally, the reduction of adherent pathogens by RFC was compared with that of fructooligosaccharides ( FOS ), galactooligosaccharides ( GOS ), and raffinose. All 4 prebiotics inhibited adhesion of both pathogens to chicken epithelial cells. Reduction of adherent Salmonella was greatest with FOS and lowest with GOS, whereas reduction of adherent C. jejuni was greater with RFC and raffinose than with FOS and GOS. These results will inform future research elucidating mechanisms important to adhesion inhibition of pathogens by RFC and other prebiotics.