Cascade polymer complexes that containa) complexing ligands of general formula IA--{X--[Y--(Z--W--K.sub.W .sub.z).sub.y ].sub.x}.sub.a (I),in whichA stands for a nitrogen-containing cascade nucleus of base multiplicity a,X and Y, independently of one another, stand for a direct bond or a cascade reproduction unit of reproduction multiplicity x or y,Z and W, independently of one another, stand for a cascade reproduction unit of reproduction multiplicity z or w,K stands for the radical of a complexing agent,a stands for numbers 2 to 12,x, y, z and w, independently of one another, stand for numbers 1 to 4,provides that at least two reproduction units are different and that for the product of the multiplicities,16.ltoreq.a.multidot.x.multidot.y.multidot.z.multidot.w.ltoreq.64holds true,b) at least 16 ions of an element of atomic numbers 20 to 29, 39, 42, 44 or 57-83,c) optionally cations of inorganic and/or organic bases, amino acids or amino acid amides as well asd) optionally acylated terminal amino groups are valuable compounds for diagnosis and therapy.