Introduction. In modern transfusion practice, both in peacetime and in military conditions, red blood cells (RBCs) are widely used as the main component of donor blood. Cryopreserved red blood cells are considered the most safe and high-quality RBC-containing environment. However, the storage period of thawed RBCs after cryopreservation is limited to 24 hours, and significantly complicates their use. Therefore, extending the storage period of thawed RBCs is relevant for the blood service. Research objective: study the RBCs morphological state and functional completeness that were cryopreserved at -40ºС and stored for 7 days at a temperature of +2ºС - +4ºС after thawing. Materials and methods. The object of the study were RBCs that were cryopreserved at -40ºС and stored for 7 days at a temperature of +2ºС - +4ºС after thawing. Deglycerolization of the thawed red blood cells, cryopreserved at -40ºС, required three time washing by using reverse cytoagglomeration. Thawed RBCs were re-suspended in lactate-sucrose-phosphate solution. After RBC thawing and storage for 7 days (186 doses) in the suspension the following indicators were studied: free hemoglobin, extracellular potassium, adenosine triphosphoric acid (ATP), 2,3-diphosphoglycerate (2,3-DPG), hematocrit, degree of hemoglobin affinity to oxygen (P50,), viscosity coefficient, osmotic stability, electrophoretic mobility of erythrocytes. as well as the total number of cells lost and recovered. Results. After storage for 7 days of suspension of thawed RBCs at a temperature of +2ºС - +4ºС indicators of free hemoglobin (0,62±0,02 g/l), extracellular potassium (2,7±0,3 mmol/l), hematocrit (0,4±0,02 l/l) were within normal limits. Osmotic resistance (0,46±0,02%), electrophoretic mobility (0,94±0,04 µm·cm·V-1·s-1) of RBCs, suspension viscosity factor (5,5±0,20mPa·С) did not exhibit changes in comparison with normal values. High levels of ATP indicators (3,0±0,2 µmol/gHb) and 2,3-DPG (10,5±1,3 µmol/gHb) were established. Indicator Р50 (24,1±1,3 hPa) corresponded to low hemoglobine affinity for oxygen. After 7-day storage at +2ºС - +4ºС total cell loss was insignificant and amounted to 5,6±0,4%. High percentage of viable thawed RBCs 94,4±0,5% was shown. Conclusions. Deglycerolization of thawed red blood cells, cryopreserved at -40ºС, by reverse cytoagglomeration, as well as use of lactate-sucrose-phosphate solution for washed RBCs resuspending promote prolongation of thawed RBCs storage period up to 7 days at +2ºС - +4ºС in viable condition.