The administration of any blood component carries with it the potential of an adverse reaction. Many times, these reactions can be blamed on the biological aspect of the blood. Because the antigen profile of blood varies among individuals, incompatabilities which are known as immune responses, may occur during transfusion. However, even when donor blood is a perfect antegenic match, it is possible for transfusion reactions to occur. These reactions are considered nonimmune, and may be linked to the collection, preparation or administration of the blood. Certain predisposing factors, such as liver or renal failure, patient size, or pre-existing disease may affect a patient's tolerance to donor blood. Nonimmune transfusion reactions involve not only refrigerated blood components, but also commercially prepared products. Below, nine reactions involving a nonimmune response are discussed.