In the title compound, C(6)H(9)N(2)S(+)·Cl(-)·CH(4)N(2)S, the 4,6-di-methyl-2-thioxo-1,2-dihydro-pyrimidin-3-ium cation is proton-ated at one of the pyrimidine N atoms. The cations are bridged by the chloride anions through a pair of N-H⋯Cl hydrogen bonds. The amino groups of each thio-urea adduct inter-act with the chloride anions through a pair of N-H⋯Cl hydrogen bonds and the S atom of another thio-urea adduct through a pair of N-H⋯S hydrogen bonds. These inter-actions result in a layered hydrogen-bonded network propagating parallel to the bc plane. Except for two H atoms, all atoms are on special positions.