The first two crystal structures of enamines derived from 1-n-alkyl-3-methyl-5-pyrazolones, namely 1-(n-hexyl)-3-methyl-4-[1-(phenylamino)propylidene]-2-pyrazolin-5-one, C19H27N3O, (I), and N,N'-bis[1-[1-(n-hexyl)-3-methyl-5-oxo-2-pyrazolin-4-ylidene]ethyl]hexane-1,6-diamine, C30H52N6O2, (II), are reported. The molecule of (II) lies about an inversion centre. Both (I) and (II) are stabilized by intramolecular N-H...O hydrogen bonding. This confirms previous results based on spectroscopic evidence alone.