Extracts of Gymnemy sylvestre (GS) exhibit hemorheological activity. The most pronounced effect was observed for GL extract in 25 wt % concentration, which (i) induced a decrease in the viscosity of blood and washed erythrocyte suspensions in the entire range of shear rates by a factor of 1,3 (ii) reduced the degree of deformability of red blood cells, (iii) increased the degree of osmotic resistance of erythrocytes by 21.3%, (iv) increased the intensity of fluorescence of DSM+ probe in erythrocyte suspensions by a factor of 1.5, and (v) decreased the degree of anisotropy, thus generally improving the viscoelastic properties of the erythrocyte membrane and preventing the thrombocyte aggregation. In this respect, the GS extract activity exceeded that of Tanakan.