Аннотация:Ability of red blood cells to spontaneously aggregate and forcedly disaggregate in flow conditions and the pair interaction of single cells as an elementary part of this process affect the blood viscosity and as a consequence determine blood flow and microcirculation in vessels and capillaries. The microrheologic properties that characterize these abilities wereassessed by diffuse light scattering and optical trapping / manipulation techniques. Blood apparent viscosity was measured using rheometry. We conducted experiments aimed to assess the effect of various blood hematocrits, temperatures and concentrationsof proaggregant macromolecules, as well as RBC membrane rigidity on RBC aggregation (RBC-A) and interaction. Relations between the obtained parameters are discussed.This work was support ed by the RFBR grant № 17-02-01200-а.