Seven different standard GAGs were shown to bind various amounts of 65Zn by gel filtration on Sephadex G-25 at pH 4.0 and pH 7.0. "Molar" zinc-binding ratios, calculated on the basis of molar bound 65Zn per hexuronic acid and sulfate of each GAG, were significantly different for C4S, C6S, DS, HA, HS, at the two pHs; however, there was no difference for HP and KS. Moreover, while the binding ratios of C4S, C6S, and DS were higher, those of HA and HS were lower at pH 4.0 than at pH 7.0. The order of increasing zinc-binding ratios was (i) HS, KS, HA, C6S, C4S, DS, HP at pH 4.0 and (ii) C6S, KS, C4S, DS, HS, HP, HA at pH 7.0.