The slow evaporation of analytical NMR samples resulted in the formation of crystals of (E)-2-({[4-(dimethylamino)phenyl]imino}methyl)-4-nitrophenol, C(15)H(15)N(3)O(3), (I), and (E)-2-({[4-(diethylamino)phenyl]imino}methyl)-4-nitrophenol, C(17)H(19)N(3)O(3), (II). Despite the small structural difference between these two N-salicylideneaniline derivatives, they show different space groups and diverse molecular packing. The molecules of both compounds are close to being planar due to an intramolecular O-H···N hydrogen bond. The 4-alkylamino-substituted benzene ring is inclined at an angle of 13.44 (19)° in (I) and 2.57 (8)° in (II) with respect to the 4-nitro-substituted phenol ring. Only very weak intermolecular π-π stacking and C-H···O interactions were found in these structures.