Abstract A carbohydrate-containing component of wheat gluten (glyc-gli) has been prepared which is toxic to coeliac intestinal mucosa. Its amino acid composition is uniquely different from that of the parent gluten and from α-gliadin. This glyc-gli material has been shown to bind to membrane components of the coeliac intestinal cell but to bind only poorly to normal intestinal cell membranes. Furthermore this binding can be interfered with by exogenous free carbohydrate suggesting that the toxic moiety of gluten acts in an analagous way to plant lectins. These data suggest that the underlying defect in coeliac disease is related to the composition of the surface membrane of the enterocyte.