The present invention provides novel crystalline forms of Deutetrabenazineand Tetrabenazine. Specific crystalline forms provided by the presentinventioninclude Deutetrabenazine Form APO-I, a co-crystal of Deutetrabenazine andquercetin; Deutetrabenazine Form APO-II, a co-crystal of Deutetrabenazine andluteolin; Tetrabenazine Form APO-I, a co-crystal of Tetrabenazine andquercetin;and Tetrabenazine Form APO-II, a co-crystal of Tetrabenazine and luteolin.Alsoprovided are pharmaceutical compositions comprising the Deutetrabenazine andTetrabenazine crystalline forms, and the use of these forms in the treatmentoftardive dyskinesia and chorea associated with Huntington's disease.