2-[(E)-(6-Amino-1,3-dimethyl-2,4-dioxo-1,2,3,4-tetra-hydro-pyrimidin-5-yl)imino-meth-yl]pyridinium chloride monohydrate.

The title compound, C(12)H(14)N(5)O(2) (+)·Cl(-)·H(2)O, is the monohydrate of the hydro-chloride of an oxopurine-derived Schiff base in which protonation took place at the pyridine N atom. The organic cation is essentially planar (r.m.s. of all fitted non-H atoms = 0.0373†à ). In the crystal, N-H⋯O and N-H⋯Cl hydrogen bonds as well as C-H⋯O and C-H⋯Cl contacts connect the different entities into a three-dimensional network. The shortest centroid-centroid distance between two pyrimidine rings is 3.6364†(9)†à .