Polyamino acids which are soluble and helical in acetic acid and dichloroacetic acid (DCA) have been observed to undergo a helix to random chain transition upon the addition of lithium salts of strong acids. The transition can be reversed by diluting the salt. Apparently only lithium cations are able to bring about the polycarbobenzoxy-L-lysine (PCBL) transition in acetic acid, whereas the anions display a varying degree of effectiveness; Clo4-> Br-> TSA-> C1-> NOs-. The lithium salts of carboxylate anions such as OAc-and TFA-do not cause polymer unwinding in acetic acid. Neither do the acids, TSA, HCl, TFA, or DCA induce the transformation in acetic acid. Poly-L-alanine (PLA) in DCA unfolds as LiBr is added, but does not unfold in the presence of 0.5M (CH3)4NBr, 0.25M CsBr, or 0.32M HCl. These results are explained on the basis of a direct interaction of the lithium salt with the polymer amide groups to form an ion-pair complex. The extent to which the anion of the ion pair can dissociate from the complex in the low dielectric constant environment determines the degree of unfolding of the polymer. The anion dissociation equilibrium presumably therefore would be in the same order as given above. Acids such as HC1 and TSA are considered to substantially protonate and ion-pair with the polymer, but do not readily dissociate the anion partner from the complex, and therefore do not produce an unstable positively charged helical structure.