The complex dietary carbohydrates, called prebiotics, have been used to control Salmonella and improve intestinal bacterial balance in broilers. Leuconostoc mesenteroides (ATCC 13146) isomaltooligosaccharides (IMO) stimulate growth of Bifidobacterium and Lactobacillus and are not used by Salmonella or Escherichia coli. We tested the efficacy of these IMO as a prebiotic. IMO, compared with fructooligosaccharides (FOS) as sole carbon source, promoted growth of chicken cecal isolates and Bifidobacterium. Cecal isolates and Salmonella typhimurium grown in mixed culture on IMO reduced the Salmonella population. Cecal isolates grown on IMO showed higher viable counts and faster growth than Salmonella, indicating a potential value for these oligomers for poultry intestinal microflora modification.