The property of oxygen transport function was investigated in blood which had been stored in solutions of "glugizir" and "zitroglucophosphate" and in erythrocyte concentrates gained from it on the noughth, 7th, 14th und 21st day of storage at -4 +/- 2 degrees C. The parameters of the oxygen binding function (oxygen content of erythrocytes, half time of haemoglobin saturation with oxygen, concentration of organic phosphate [2.3 diphosphoglycerate and adenosine triphosphate] and those of inorganic phosphorus were determined in erythrocytes. During storage for more than 21 days no significant differences could be detected in the property of oxygen transfer between erythrocytes of stored blood and erythrocyte concentrate, with the values for storing in zitroglucophosphate being somewhat higher. Problems of applying all components of donor blood efficiently are discussed. In performing an adequate haemotherapy with blood components the importance of a functional condition of erythrocytes and oxygen balance in the organism of the receiver should be considered. The necessity of transfusing erythrocyte concentrate in the therapy of anaemias of different genesis is emphasized and the differences in applying concentrates in different plasma solutions are referred to. By transfusing concentrates the effectiveness of hemotherapy are elevated and the rate of complications and side-effects of whole blood are diminished.