The dihydrotetrabenazine (DTBZ) was synthesized by reduction of tetrabenazine with sodium borohydride in ethanol. Crystals suitable for X-ray analysis were obtained from a mixed solution of dichloromethane and ethanol in a five-to-one volume ratio. The crystal is monoclinic, space group P2(1)/c with crystallographic parameters: a = 15.0129(14) angstrom, b = 12.5677(12) angstrom, c = 9.7715(9) angstrom, beta = 98.556(2)degrees, mu = 0.078 mm(-1), V = 1823.1(3) angstrom(3), Z = 4, Dc = 1.164 g/cm(3), F(000) = 696, T = 296(2) K. The X-ray analysis and the chiral HPLC show that the DTBZ prepared by our method consists of (2R,3R,11bR) and (2S,3S,11bS) enantiomers.