The title compound, C(15)H(15)N(3)O(2), contains benzonitrile and 4,4-dimethyl-2,6-dioxocyclo-hexyl-idene groups connected via a hydrazinyl group. The structure is in the hydrazone tautomeric form in the solid state. The benzonitrile and hydrazinyl groups (3-hydrazinylbenzonitrile) are essentially coplanar with an r.m.s. deviation of 0.016 Å. Intra-molecular N-H⋯O hydrogen bonding helps to stabilize the mol-ecular structure, and weak inter-molecular C-H⋯O hydrogen bonding is present in the crystal structure.