The title compound, potassium bis(ethylenediamine-N,N')copper(II) hexacyanoferrate(III), K[Cu(C2H8N2)(2)]-[Fe(CN)(6)], contains [Cu(en)(2)](2+) and [Fe(CN)(6)](3-) complex ions, where en is ethylenediamine. The Fe-III and K+ ions lie on twofold axes and the Cu-II atom lies on an inversion center. The [Cu(en)(2)](2+) ion has square-planar coordination with a mean Cu-N distance of 1.992 (2) Angstrom and the [Fe(CN)(6)](3-) ion has distorted octahedral coordination with a mean Fe-C distance of 1.947 (2) Angstrom.