Four silica-based adsorbents were prepared from covalent attachment of four carbohydrates : i.e. maltose, cellobiose, N-acetyl-D-glucosamine and p-aminophenyl-beta-D-glucopyranoside, respectively. These adsorbents possess either terminal D-glucose or N-acetyl-D-glucosamine as the ligand on their surfaces with a ligand density ranging from 20 to 29.2 mu mol g(-1). The binding of the glucose-specific lectin, concanavalin A (Con A), to the immobilized ligand on the silica surface depended on the configuration of the immobilized glucose and the linkage of the glucose to the support. Con A showed strong affinity for maltose-immobilized silica, which contains terminal alpha-o-glucose, and p-aminophenyl-beta-D-glucopyranoside-immobilized silica. On the other hand, Con A showed no affinity for cellobiose-immobilized silica, which contains terminal beta-D-glucose groups, and N-acetyl-D-glucosamine-immobilized silica. The binding constants for the interactions between Con A and immobilized ligands were determined. The columns packed with the resultant affinity adsorbents were then adopted for the purification of Con A from Jack bean meal. As the diluted NaCl extract of jack bean meal was applied to the column packed with maltose-immobilized silica, a 13.2-fold purification was achieved by stepwise-elution.