In the title compound, C(16)H(15)ClN(2)OS, the hydrazine group is twisted slightly: the C-N-N-C torsion angle is 175.46 (13)°. The dihedral angle between the two terminal aromatic rings is 87.01 (8)°. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R(2) (2)(8) loops. The dimers are further linked by weak C-H⋯π inter-actions.