In the title compound, C(15)H(17)N(3)O, the 1H-imidazo[4,5-c]quinoline ring system is approximately planar, with a maximum deviation of 0.036 (1) Å. The C-N-C-C torsion angles formed between this ring system and the isobutyl unit are -99.77 (16) and 79.71 (17)°. In the crystal, inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into chains along the c axis.