The crystal and molecular structure of the Methyl-2,7,7-trimethyl-4-phenyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3 carboxylate, C20 H23 NO3, has been determined by X-ray diffraction. Crystals are monoclinic, space group P21/n; a = 9.646(2), b = 16.586(2), c = 11.111(1) Å, <FONT FACE=Symbol>b</FONT> = 102.35(1)°, Z = 4. The conformation of the 1,4-dihydropyridine ring (1,4-DHP) is described in trms of the torsion angles about the intraring bonds. The molecules are linked by intermolecular bond between the N atoms and the pirymidine O3 atom of a neighboring molecule [N1....O3: 2.865(4) Å]