In the title mol-ecular salt, 1,3-dimethyl-2,6-dioxo-2,3,6,7-tetra-hydro-1H-purin-9-ium aqua-tri-chlorido-zincate(II), (C7H9N4O2)[ZnCl3(H2O)], the fused ring system of the cation is close to planar, with the largest deviation from the mean plane being 0.037 (3) Å. In the complex anion, the ZnII cation is coordinated by three chloride ions and one oxygen atom from the water ligand in a distorted tetra-hedral geometry. In the crystal, inversion dimers between pairs of cations linked by pairwise N-H⋯O hydrogen bonds generate R 2 2(10) rings. The anions are linked into dimers by pairs of O-H⋯Cl hydrogen bonds and the respective dimers are linked by O-H⋯O and N-H⋯Cl hydrogen bonds. Together, these generate a three-dimensional supra-molecular network. Hirshfeld surfaces were generated to gain further insight into the packing.