In the title compound, C(17)H(16)N(2)OS, the central thia-zolidin-4-one ring forms dihedral angles of 66.49 (9) and 79.45 (6)° with the two methyl-substituted benzene rings. In the crystal, mol-ecules are stacked in columns along the b axis through C-H⋯π inter-actions. The H atoms of one of the methyl groups are disordered over two orientations with equal site occupancies.