The critical overlapping concentration c* has been studied in the dynamic state (by viscometry) and in the static state (by light scattering). An increase of the shear rate of the solution provokes an increase of c* in the case of linear polymers. In the case of a highly branched polymer the shear rate has no influence on its critical concentration. The scaling law between c* and the molecular mass for a given polymer-solvent system presents two different exponents, depending on the molecular mass region of the polymer.