The crystal structure of diaquabis(L-dihydroorotato)zinc(II) reveals that the ureido nitrogen adjacent to the coordinated carboxylate does not coordinate to the zinc atom in contrast to the situation in zinc(II) complexes of orotate. Moderately strong intramolecular hydrogen bonds between two coordinated water molecules and noncoordinated carboxylate oxygen atoms stabilize the coordination geometry. The higher pK(a) of the ureido group of dihydroorotate and its extra flexibility probably account for it forming a unidentate rather than bidentate interaction with the zinc(II) atom.