We investigated the action of mexicor on functional indices of erythrocytes and the structure of myocardial microcirculation in rats suffered from traumatic brain injury (TBI). At 3, 7 and 12 day after TBI we measured the concentration of 2,3-diphosphoglycerate (2,3-DPG), the degree of erythrocyte aggregation and their electrophoretic mobility (EPME) in the blood of rats, and also analyzed sections of left ventricular myocardium. During the first day after the TBI we observed a decrease in EPME, an increase of erythrocyte aggregation and an increase of 2,3-DFG concentration in erythrocytes compared with intact animals. Intraperitoneal injection of mexicor led to an increase of EPME, 2,3-DPG level and reduce an aggregation of erythrocytes, which was the most pronounced during the 3—7 day of post-traumatic period. Improved functional parameters of erythrocytes were combined with the dynamics of regenerative processes in the heart. Intraperitoneal injection of mexicor restrained architectonic damage of microvasculature and cardiomyocytes ultrastructure of the myocardium of the left ventricle of the heart.