Antibody detection and identification are processes that are commonly performed in the transfusion service before transfusion of allogeneic red blood cells (RBCs). Antibody identification usually follows the discovery of a positive antibody detection test, or other factors such as ABO serum/cell discrepancy or an incompatible crossmatch. Antibody identification is a necessary practice in blood banking to determine the suitability of blood products for transfusion on an individual basis. When the presence of multiple antibodies is suspected, several methods, including neutralization of patient's plasma, titration, elution, chemical or enzyme treatment of reagent RBCs, and adsorption with allogeneic RBCs, may be used to separate and properly identify other atypical antibodies that are present in a single serum or plasma sample. This review will focus on the use of allogeneic adsorption to identify antibody specificities in a patient's sample.