In the title compound, C(7)H(9)ClN(4), the 3-chloro-6-hydrazinylpyridazine unit is planar (r.m.s. deviation = 0.0219 Å) and is oriented at a dihedral angle 4.66 (27)° with respect to the propan-2-yl-idene group. In the crystal, the mol-ecules are linked into non-planar dimers due to a crystallographic twofold rotation via N-H⋯N hydrogen bonds with R(2) (2)(8) graph-set ring motifs.