The crystal structure of the title compound has been determined by single crystal X-ray diffraction methods. C 27H 29N 2O 3Cl.HCl is one of the cinchona alkaloids. It crystallizes in the space group P2 12 12 1 with a = 11.745(3), b = 12.353(6), c = 17.253(6) Å and Z = 4. The structure was refined to a final R value of 0.062 for 2155 observed reflections. The C-N distances are unequal in the quinoline ring system. In quinulidine ring, the bonds around N are more tetrahedral. The spatial arrangement and torsion angles show the open conformation of the molecule. The molecular packing is stabilized by hydrogen bonding