Adherence of enterobacteria on intestinal epithelial cells is considered a major pathogenic mechanism of infantile diarrhea. In 36 of 40 infants with diarrhea of more than five days' duration, bacterial organisms were isolated from the duodenum. Adherence of these bacteria was investigated by different methods: hemagglutination of 0 + human red blood cells was used as a screening; adherence of bacteria on isolated intestinal epithelial cells was studied by a radiolabeled filtration assay, observation of epithelia under the light microscope and calculation of the number of bacteria/cell was counted. The correlation between these methods was high; 20 of 36 strains showed adherence by all methods. The cell-free carbohydrate fraction of carrot soup and a 2% solution of carob, the fruit of the Mediterranean locust tree, were able to block hemagglutination and adherence of Escherichia coli on isolated intestinal epithelial cells to a great extent. The active blocking agent was found in the oligosaccharide fraction of the carob solution. Blockage of adherence of bacteria isolated from the upper small intestinal tract of children with severe, protracted diarrhea could explain the therapeutic effectiveness of empirically proven diarrheal remedies.