Abstract: Concentration effect in the high performance GFChas been investigated. The study of the contraction of hydromechanical volume has been made htough determination of the varying values of the being clution volume with the change of concentrations.On the case of higher molecular weights and higher concentration, the curve of V_c-Cin good solvent crosses with the V_c-Ccurve in bad loivend for the samples with the same molecular weight. The point of intersection of the curves shifts to the direction of the lower concentration as the molecular weight increases.