A crude polysaccharide that hemolyzed human red blood cells of the ABO types was isolated from the condensed tannin fraction of Sorghum bicolor. It contained primarily 2-hydroxybenzoic acid and glucose and had a molecular weight of greater than 6000. Limit hemolytic activity for each of four blood group cells corresponded to a range of 110-27 micrograms of carbohydrate per assay.