The crystal structure of bisnitrito-2,2′-bipyridylcopper(II) has been determined by X-ray diffraction methods and refined by a full-matrix least-squares procedure. The monoclinic unit cell space group P21/c has dimensions a= 8·393, b= 10·080, c= 15·136 Å, β= 110·04°, for Z= 4. The copper atom is surrounded by a nearly square planar arrangement of the two bipyridyl nitrogen atoms at 1·98 Å and an oxygen from each nitrite ion at 1·99 Å. The second oxygen of each nitrite is then involved in weak co-ordination at a longer Cu-O distance of 2·49 Å, the latter making an appreciable angle (32°) with the normal-to-plane of the in-plane bonds. The molecular symmetry is C2 and the bipyridyl ligand is nearly planar, the twist about 2,2′-carbon bond being 3·2°.