In the title mol-ecule, C(13)H(15)N(3)O(2), the dihedral angle between the mean plane of the 1,3-dioxolane group and the 2-hydrazino-7-methyl-isoquinoline unit is 85.21 (5)°. The conformation of the mol-ecule is influenced by bifurcated N-H⋯(O,O) and N-H⋯N intra-molecular hydrogen bonds. In the crystal structure, mol-ecules are linked via inter-molecular N-H⋯O hydrogen bonds, forming extended chains along [001].