Shiga toxins (Stx) are virulence factors produced by selected bacteria pathogenic for humans. These multicomponent protein complexes are among the more potent toxins known. As inhibitors of eukaryotic protein synthesis, these toxins selectively inactivate ribosomes in an enzymatic manner. Specificity of cell targeting is determined by the high-affinity binding of Stx to its receptor, a glycosphingolipid (Gb3) located in the plasma membrane or some eukaryotic cells. Elaborated by food-borne E. coli O157:H7 bacteria, isotypes of Stx (Stx1 & Stx2) are required for the ensuing vascular changes in humans, including hemorrhagic colitis and renal hemolytic uremic syndrome. Experimental therapeutic intervention of Stx-associated disease includes the Stx receptor immobilized on biologically inert particles designed for oral presentation.