The asymmetric unit of the title compound, (C14H17N2S2)-[Ru(C10H14)Cl-3], contains a 1,3-bis(thiophen-2-ylmethyl)-3,4,5,6-tetrahydropyrimidinium cation and a trichlorido(eta(6)-p-cymene) ruthenate(II) anion. The Ru atom exhibits a distorted octahedral coordination with the benzene ring of the p-cymene ligand formally occupying three sites and three chloride atoms occupying the other three sites. The N-C bond lengths of the N-C-N unit of the pyrimidinium cation are shorter than the average single C-N bond length of 1.48 angstrom, thus showing double-bond character, indicating a partial electron delocalization within the N-C-N fragment. The pyrimidine ring has an envelope conformation. Four intermolecular C-H center dot center dot center dot Cl hydrogen bonds generate a three-dimensional hydrogen-bonded framework.