In the title compound, C(19)H(18)N(4)O(2), the 1,8-naphthyridine ring system is essentially planar [r.m.s. deviation = 0.011 (3) Å]. The dihedral angle between the naphthyridine ring system and the phenyl ring is 28.95 (7)°. The carbohydrazide H atom is involved in an intra-molecular N-H⋯O hydrogen bond, forming a six-membered hydrogen-bonded ring. In the crystal, the mol-ecules arrange themselves into centrosymmetric dimers by means of inter-molecular C-H⋯O hydrogen bonds.