The present invention generally relates to an apparatus, method, system for the determination of the aggregation rate of red blood cells. More specifically, the invention concerns a method, system, and the relative apparatus used to determine the aggregation rate of red blood cells, and other parameters related to these, such as viscosity, deformability, elasticity, density, in the field of in vitro medical analyses, using optical systems after or during inducted forces for red blood cell disruption and redistribution generated by ultrasound waves.