Using a scintigraphic technique based on anautologous injection of . 99m. Tc-labelled erythrocytes, we have evaluated the efficiency of different exsanguination procedures in the upper limb of ten healthy male volunteers. The methods were elevation alone, the use of the Esmarch bandage or a gauze bandage, the Pomidor roll-cuff, the squeeze method and the Urias bag. The various procedures gave the following median percentage reductions of blood volumes: elevation for 5 seconds 44%, 15 seconds 45%, 30 seconds 46%, 60 seconds 46% and 4 minutes 42%, the Esmarch bandage 69%, a gauze bandage 63%, the Pomidor roll-cuff 66%, the squeeze method 53%, and the Urias bag 57%. With regard to elevation alone no significant differences were found. All the external methods were significantly more effective than elevation alone. Overall, the squeeze method was found to be the best method of exsanguination before inflation of a tourniquet, because it is effective, fast, practical and inexpensive