This session will describe three cases of acute hemolytic anemia, the laboratory results, clinical conditions, and the methods used for therapy. Hyperhemolysis, with or without the presence of underlying red cell antibodies, is frequently overlooked or misinterpreted by the attending staff. While pernicious autoimmune hemolytic anemia is associated with Rh specificities, acute and frequently fatal autoimmune hemolytic anemia is associated with glycophorin receptors (MNS and Ge blood group and Pr receptors). Early recognition of a serological specificity may suggest the most appropriate therapeutic methods. The high mortality rate of these and similar cases will be discussed.