When disodium sulfate (Na2SO4) is added to dilute aqueous solution of poly(vinylpyrrolidone) (PVP) or poly(vinyl alcohol)(PVA), contraction of polymer coil occurs by dehydration and, therefore, intrinsic viscosity, [Z], of these polymers decreases as shown in Fig.2. On the other hand, viscosities of concentrated solutions of these polymer's changed by the addition of Na2SO4, as shown in Figs.3, 4 and 5. Viscosities of concentrated solutions of PVP decrease with increasing concentration of Na2SO4, and the anomalous viscosity disappears as a result of Newtonian flow. On the other hand, viscosities of concentrated solutions of PVA increase with incresing concentration of Na2SO4, and elastic gel is formed by the addition of more salt. It is concluded that intermolecular hydrogen bonding occurs by dehydration of PVA and enhances the anomalous viscosity.The variation of the viscosity of concentrated solutions of these polymers with temperature is found to be expressed by Andrade's equation, n= A ex p (eIRT). In the case of PVP, as the viscosity decreases rapidly by enhancement of dehydration and by shrinking of polymer coil, temperature coefficient, e, increases with increasing concentration of Na2SO4 as shown in Fig.9. In the case of PVA, the parameter, e, decreases with increasing concentration of salt as shown in Fig.9, because the dehydration by Na2SO4 increases the viscosity of PVA solution as mentioned above.When sodium dodecyl sulfate (SDS) is added to solution of these polymers, the viscosities of the solutions of PVA and PVP increase, because SDS combinds with these polymers in the concentrated solution as well as in dilute solution as shown in Fig.6. It is suggested that mechanism of SDS-interaction with polymers differs from that of interaction of Na2SO4 irrespective of the existence of common hydrophilic group.