A new orthorhombic polymorphic modification of the title compound (alternative name: cis-transoid-cis-2,5,8,15,18,21-hexaoxatricyclo[20.4.0.0(9,14)]hexacosane), C(20)H(36)O(6), has been found and is compared with the previously known monoclinic modification. In the structures of the two polymorphs, the crown-ether molecules are centrosymmetric and reveal essentially the same molecular shape but different packing motifs.