Autologous blood transfusion--transfusion to the patient of his or her own blood--is of increasing importance in transfusion practice. There are three main techniques: pre-deposit, in which patients donate blood over a period of time in preparation for elective surgery; preoperative isovolaemic haemodilution, in which blood is removed in theatre immediately preoperatively and volume replacement is given, the blood being reinfused postoperatively; and salvage transfusion - the harvesting of blood shed at surgery or in similar circumstances, which is reinfused immediately or after concentration and purification. All these techniques can play a part in rendering transfusion safer and in economising on scarce supplies of donor blood.