In the title compound, C(11)H(9)ClN(2)OS, the thia-zole ring is nearly planar (r.m.s. deviation = 0.003 Å) and forms a dihedral angle of 64.18 (7)° with the bezene ring. In the crystal, inversion dimers linked by pairs of N-H⋯N(t) (t = thia-zole) hydrogen bonds generate R(2) (2)(8) loops.