The isometric pyrochlore structure, A2B2O7, is generally susceptible to radiation damage, but certain compositions are remarkably resistant to radiation damage. In the binary system Gd2(Ti22xZrx)O7, the radiation resistance increases dramatically with the substitution of Zr for Ti, until the pure end member Gd2Zr2O7 cannot be amorphized, even at doses as high as; 100 dpa. Although zirconate pyrochlores are generally considered to be radiation resistant, we report results for the amorphization of a zirconate pyrochlore La2Zr2O7 by ion beam irradiation; 5.5 dpa at room temperature!. The critical amorphization temperature Tc is low,; 310K. The susceptibility to ion-beam-induced amorphization and structural disordering for zirconate pyrochlores is related to the structural deviation from the ideal fluorite structure, as reflected by the x parameter of the O48f.