A lectin in gluten was detected by agglutination of papain-treated human erythrocytes. A partially purified lectin preparation was obtained by chromatography on immobilized ovalbumin. This fraction showed the same sugar specificity as wheat germ agglutinin (WGA). There was no indication of lectins with carbohydrate specificities different from WGA in the various gluten fractions examined. Small amounts of the gluten lectin was then isolated by using an affinity column with specificity for WGA. Analyses of this gluten lectin by sodium dodecyl sulphate-gel electrophoresis showed bands with the same mobility as that of purified WGA. Our results indicate that the lectin properties of gluten are due to traces of WGA. This finding is relevant for theories about the pathogenesis of coeliac disease.