The asymmetric unit of the title molecular salt, C3H10N+·C12H9N4O7
− [alternative name: trimethylammonium 5-(2,4-dinitrophenyl)-1,3-dimethyl barbiturate], contains one anion and two half-occupancy cations. The cations are disordered about inversion centres. The tetrahydropyrimidine ring is essentially planar [maximum deviation = 0.007 (2) Å] and forms a dihedral angle of 41.12 (6)° with the plane of the benzene ring. In the crystal, N—H⋯O hydrogen bonds link the cations to the anions.