The title compound, [HgCl(2)(C(4)H(5)N(3))](n), features a two-dimensional network parallel to (001) that is based on an Hg(II) atom octahedrally coordinated by four μ(2)-Cl atoms and two μ(2)-2-amino-pyrimidine (apym) ligands in trans positions, yielding a distorted HgCl(4)N(2) octa-hedron. The coordination network can be described as an uninodal 4-connected net with the sql topology. The Hg(II) ion lies on a site of -1 symmetry and the apym ligand lies on sites of m symmetry with the mirror plane perpendicular to the pyrimidine plane and passing through the NH(2) group N atom. This polymeric structure is stabilized by N-H⋯Cl hydrogen bonds and columnar π-π stacking of pyrimidine rings, with a centroid-centroid distance of 3.832 (2) Å.