In the title compound, C(16)H(13)ClN(4)S, the thienopyridine fused-ring system is nearly planar (r.m.s. deviation = 0.0333 Å) and forms a dihedral angle of 4.4 (3)° with the attached dihydro-imidazole ring (r.m.s. deviation = 0.0429 Å) allowing for the formation of an intra-molecular (exocyclic amine)N-H⋯N(imine) hydrogen bond. The benzene rings of the disordered (50:50) -N(H)-C(6)H(4)Cl residue form dihedral angles of 59.1 (3) and 50.59 (15)° with the fused ring system. In the crystal, (imidazole amine)N-H⋯N(pyridine) hydrogen bonds lead to a supra-molecular helical chain along the b axis. The chains assemble into layers (ab plane) with inter-digitation of the chloro-benzene rings which results in weak C-H⋯Cl inter-actions in the c-axis direction.