Many studies have demonstrated the dietary effects of non-starchpolysaccharides (NSP) on animal health and performance. Mannanoligosaccharide (MOS), a NSP, has been shown to maintain gut integrity by binding mycotoxins and blocking pathogens from attachment to the epithelial tissue along the gastrointestinal (GI) tract, and stimulating the immune system. Two experiments were conducted to evaluate: 1) effect of MOS on the colonization of coliform bacteria in the GI tract of broiler chicks; and 2) the effect of MOS in suppressing the effects of aflatoxins. In Experiment 1, lactose and MOS were compared in the reduction of coliform bacteria in the ceca of the GI tract in chicks. Lactose and MOS were included separately in a corn-soybean diet and fed to broiler chicks for 28 days. In Experiment 2, male broiler chicks were selected randomly and placed in a 2 χ 2 factorial design arrangement (0 and .1% MOS and 0 and 5 ppm aflatoxin). MOS and aflatoxin were included in a com-soybean-based diet. Each dietary treatment was fed to three pen replicates of 10 chicks each for 21 days. Compared to the control, caecal bacterial load was significantly reduced by 3 logs with the addition of MOS to the diet. The effects of MOS on aflatoxin-contaminated feed were seen in weekly body weight, feed conversion, relative liver, proventriculus, and heart weights. In conclusion, MOS was effective in binding aflatoxin and blocking the attachment of coliform bacteria.