The initial barrier to the transplantation of pig organs to human is hyperacute rejection (HAR). HAR was initiated by the conjugation of human natural antibodies (XNA) with the Gal-α1,3-Gal which is thought to be the major xenoantigenic epitope present on pig tissues. Removal of antibodies directly against that structure may be critical to the success of pig to human xenotransplantation. The lectin GS-I-B₄ was used to screen phage-displayed peptide library XCX₁₅ and identified a peptide mimetic of Gal-α1,3-Gal. A phage bearing the peptide SCTALSFPSFAFLARGT has been identified to bind human natural antibody strongly. This binding reaction can be competitively inhibited by melibiose. The peptide can also inhibit the human natural antibody-mediated agglutination of pig RBCs.