At low pH, red blood cells (RBCs) are unable to maintain their disc shape and become stomatocytes. At the same time, at pH 5.0 of a sulphate medium, under conditions of mechanical mixing of the cell suspension, RBCs are partially retransformed into discoid forms, whereas in a chloride medium (pH 5.0) this transformation is observed to a high degree.This indicates that the chloride-binding sites of RBC membranes may be an additional link in the regulation of the shape of RBC under conditions of mechanical action on the cell suspension. The work investigated the change in the RBC shape at a normal pH value (7,4) due to the replacement of Na2SO 4 in the medium with NaCl and recording an increase in the intensity of fluctuations in optical density (OD), as an indicator of an increase in the level of discoid cells (normocytes) in a stirred cell suspension. It has been 3 established that in a medium containing Na2SO4 (110 mmol/l), RBCs are transformed into small stomatocytes within ~20 s. With an increase in NaCl concentration in the range of 15-105 mmol/l, an increase in the level of discoid cells is noted. Increasing the NaCl concentration from 105 to 150 mmol/l, on the contrary, causes a decrease in the level of discoid cells. With the exception of mechanical mixing in a medium with NaCl concentrations of 30-90 mmol/l, RBCs are morphologically stomatocytes. Whereas in a medium containing 150 mmol/l NaCl, RBC are represented by disc-echinocytes and echinocytes. The results obtained show that mechanical mixing of the cell suspension promotes the retransformation of stomatocytic RBCs into discoid forms. The weakening of the retransforming efficiency of mixing with an increase in the NaCl concentration in the medium from 105 to 150 mmol/l and the development of echinocytosis at 150 mmol/l NaCl indicates the existence of 2 types of sites for chloride. Сhloride binding to type 1, at a NaCl concentration in the medium of 15-105 mmol/l, leads to the establishment of discoid forms of RBC. Chloride binding to type 2 sites, at a NaCl concentration in the medium of 105-150 mmol/l, leads to the development of echinocytosis. The retransforming property of mechanical stirring may be associated with a change in the degree of chloride binding to these types of sites.