Vicia villosa lectin (VVL) includes a family of tetrameric glycoproteins consisting of combinations of A and B subunits, though the dominant isolectins in our preparations appear to be B subunit-rich. VVL recognizes α- or β-linked terminal N-acetylgalactosamine, especially a single α-N-acetylgalactosamine residue linked to serine or threonine in a polypeptide (the Tn antigen). Binding may also require specific amino acid sequences at the receptor site of glycosylation. This agarose-bound VVL is prepared using affinity-purified lectin and heat stable, cross-linked 4% agarose beads. The attachment of the lectin through a hydrophilic spacer arm to the beads is carefully controlled to preserve the activity and minimize conformational changes to the bound lectins. The recommended inhibiting/eluting sugar is 200 mM N-acetylgalactosamine.