Different optical techniques are widely used for the characterization of red blood cells (RBC) aggregation. Advantages of these techniques are in their relative simplicity and possibility to analyze a large number or single cells simultaneously without mechanical contact with investigated red blood cells. RBC aggregability refers to the cells' ability to form multicellular aggregates in the presence of different plasma proteins or macromolecules. Opposing forces determine the extent of aggregation by: the repulsive force between the negatively charged cells, the cell-cell adhesion induced by the macromolecules, and the disaggregating flow-induced shear stress. Kinetic and dynamic features of the cells interaction can characterize the RBC aggregation process. In our previous publication, we used de Gennes' approach that describes macromolecules behavior in the space between two solid surfaces for analysis of the kinetics of rouleaux formation. The present study was undertaken to examine the RBC aggregation in dextran 150 kDa solution, in the light of de Gennes' model, in a concentrated RBC suspension using the diffuse light scattering technique as well on the single cell level in a highly diluted suspension with pairs of the cells using the optical tweezers. We demonstrated that the kinetics (timing process) and the mechanical features (forces balance characterization) of dextran 150-induced RBC aggregation are not identical according to their contribution to the aggregation process. Optical methods provided handy tools to study the kinetic and dynamic peculiarities of RBCs aggregation and disaggregation, which can be extremely useful for controlling the blood microcirculation especially in cases of hemorheological disorders.