Red cells are the most important and usually the only necessary part of transfused whole blood. Transfusion of concentrated red cells involves several advantages for the recipient (decreased volume load, fewer transfusion reactions, better antianemic effect per unit). The plasma which is separated from whole blood during the preparation of packed red cells can be used for fractionation or for the preparation of platelet concentrates and other special products. The increasing need for blood components makes the substitution of whole blood by packed red cells for transfusion purposes mandatory. The only rare indication for whole blood is fresh blood (i.e. blood up to 48 hours after donation). Red cell concentrates with a hematocrit of 70% are particularly suitable for general use, since the viscosity still allows transfusion without difficulties. With regard to quality and storage time of red cells there is no difference between packed cells and whole blood.