Immobilization of antibodies by their oxidized sugar chain on aminated supports is a very efficient methodology to have a properly oriented antibody. However, these supports may behave as anionic exchangers, producing the unspecific adsorption of other proteins and reducing the selectivity of the system. To overcome this problem, we have proposed two solutions based in tailor-made support surfaces to immobilize antihorseradish peroxidase (HRP). The first solution was the use of supports having a very low amount of amino groups. These amino groups need to be very reactive with the aldehyde groups generated in the protein sugar chains to be efficient. Using supports having 7 mu mol EDA/g (e.g., ethylenediamine modified glyoxyl-agarose), the antibody may be immobilized, keeping over 90% of the anti-HRP functionality. Second, by mixing amino groups and carboxylic groups, a neutral surface of the support has been generated. Again, this support has been unable to adsorb proteins while oxidized anti-HRP could be immobilized, giving functional anti-HRP antibodies. Both preparations retained 100% functionality after 2 months of storage at 4 degrees C. This way, the tailoring of the support surfaces has permitted solving some limitations of the immobilization of sugar-chain oxidized antibodies on primary amino supports.