In the centrosymmetric dinuclear title complex, [Hg(2)Cl(4)(C(12)H(9)N(3)O(2))(2)], the Hg(II) ion is in a distorted square-pyramidal coordination environment formed by the N atoms of the diimine ligand, two bridging Cl atoms and one terminal Cl atom. One of the bridging Hg-Cl bonds is significantly longer than the other.