In the title compound, C(11)H(9)BrN(4)S, the 1,2,4-triazole ring is essentially planar (r.m.s. deviation = 0.020 Å) and makes a dihedral angle of 29.1 (5)° with the bromo-benzene ring. The 3,6-dihydro-1,3,4-thia-diazine ring adopts a twist-boat conformation. In the crystal, mol-ecules are linked by C-H⋯N inter-actions into sheets lying parallel to the (010) plane. The same N atom accepts two such hydrogen bonds.