In the title compound, C23H20N3OS+ center dot Br (-), the dihydrothiazole ring (r. m. s. deviation = 0.015 angstrom) is twisted with respect to each of the C-and N-bound phenyl rings and the hydroxybenzene ring, making dihedral angles of 76.0 (2), 71.2 (2) and 9.8 (2)degrees, respectively. In the crystal, inversion-related molecules are linked by association of the bromide ions with the cations via N-H center dot center dot center dot Br and O-H center dot center dot center dot Br hydrogen-bonding interactions. These molecules run in channels parallel to the a axis through face-to-face pi-pi stacking interactions between the hydroxybenzene rings [centroid-centroid distances = 3.785 (3) angstrom] which, in turn, are connected into layers parallel to (110) by weak C-H center dot center dot center dot center dot interactions. A small region of electron density well removed from the main molecule and appearing disordered over a center of symmetry was removed with PLATON SQUEEZE [Spek (2009). Acta Cryst. D65, 148-15] following unsuccessful attempts to model it as plausible solvent molecule. The nature of the solvent was not known and hence, this is not taken into account when calculating Mr and related data.