If antibodies present in the recipient’s serum are incompatible with the donor’s cells, a transfusion reaction will result. This usually takes the form of an acute haemolytic reaction. Severe immune-related transfusion reactions due to ABO incompat- ibility result in potentially fatal complement-mediated intra- vascular haemolysis and multiple organ failure. Transfusion reactions from other antigen systems are usually milder and self-limiting. Febrile transfusion reactions are non-haemolytic and are usually caused by a graft-versus-host response from leukocytes in transfused components. Such reactions are associated with fever, chills or rigors. The blood transfusion should be stopped immediately. This form of transfusion reaction is rare with leu- kodepleted blood.