Intrinsic viscosities of poly-L-glutamic acid at pH 8.8 and of poly-L-lysine at pH 3.2 in the presence of salts which are typically representative of lyotropic series are presented. Viscosities decrease continuously with increasing salt concentration and their temperature coefficients are negative. The ranking of cations and anions for decreasing the intrinsic viscosity of poly-L-glutamic acid and poly-L-lysine respectively, corresponds to the ranking for ion binding to isoelectric gelatin.