THE TITLE COMPOUND [SYSTEMATIC NAME: 1-meth-oxy-2-(3-methyl-but-2-en-yl)-9H-carbazole-3-carbaldehyde], C(19)H(19)NO(2), is a natural carbazole which was isolated from the twigs of Clausena lansium. The carbazole ring system is essentially planar with a mean deviation of 0.0068 (10) Å. The aldehyde substituent is approximately co-planar with the attached benzene ring with a torsion angle of -8.58 (14)°, whereas the meth-oxy group is rotated out of the benzene plane with a torsion angle of -82.17 (11)°. The dihedral angle between the mean planes of the 3-methyl-2-butenyl group and the carbazole ring is 88.06 (5)°. An inter-molecular N-H⋯O inter-action connects the mol-ecules into a chain along the a axis. The crystal is further consolidated by a C-H⋯O hydrogen bond and two π-π inter-actions with centroid-centroid distances of 3.6592 (6) and 3.7440 (6) Å.