The agglutination of a selection of bacteria by some lectins was examined. The lectin from Codium fragile agglutinated seven strains of Salmonella typhimurium. The lectin from Helix pomatia agglutinated eight of 12 strains of Listeria monocytogenes and a further two strains gave a weak agglutination reaction. Helix pomatia lectin conjugated to magnetic microspheres enabled the adsorption of L. monocytogenes from suspension with subsequent elution by the competing ligand N-acetyl galactosamine. Affinity chromatography of a suspension of L. monocytogenes through a column of H. pomatia lectin immobilized on agarose, also adsorbed cells and enabled subsequent elution with N-acetyl galactosamine. The column technique enabled the more rapid adsorption of bacteria perhaps because of improved interactions between bacteria and immobilized lectin.