The title compound, C(15)H(15)N(3)O(2), contains benzonitrile and 4,4-dimethyl-2,6-dioxocyclohexylidene 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 angstrom. Intramolecular N-H center dot center dot center dot O hydrogen bonding helps to stabilize the molecular structure, and weak intermolecular C-H center dot center dot center dot O hydrogen bonding is present in the crystal structure.