In the title heteronuclear Zn(II)-Ho(III) complex (systematic name: {μ-6,6'-dimeth-oxy-2,2'-[ethane-1,2-diylbis(nitrilo-methyl-idyne)]diphenolato-1κ(4)O(1),O(1'),O(6),O(6'):2κ(4)O(1),N,N',O(1'))-μ-nitrato-1:2κ(2)O:O'-dinitrato-1κ(4)O,O'-holmium(III)zinc(II)), [HoZn(C(18)H(18)N(2)O(4))(NO(3))(3)], with the hexa-dentate Schiff base compartmental ligand N,N'-bis-(3-methoxy-salicyl-idene)ethyl-enediamine (H(2)L), the Ho and Zn atoms are triply bridged by two phenolate O atoms of the Schiff base ligand and one nitrate ion. The five-coordinate Zn atom is in a square-pyramidal geometry with the donor centers of two imine N atoms, two phenolate O atoms and one of the bridging nitrate O atoms. The Ho(III) center has a ninefold coordination environment of O atoms, involving the phenolate O atoms, two meth-oxy O atoms, two O atoms from two nitrate ions and one from the bridging nitrate ion. Weak inter-molecular C-H⋯O inter-actions generate a two-dimensional double-layer structure.