A solid-phase immunoadsorbent column using blood group A trisaccharide was tested in vitro and in vivo in dogs. This column was demonstrated to specifically remove anti-A antibody from human plasma in vitro and in vivo dogs specifically immunized with synthetic human blood group A trisaccharide. These studies indicate that this technique will be useful in removing anti-A and B antibody in marrow transplant recipients of incompatible marrow.