Three new alkaloids were isolated from the root-wood of Brucea mollis var. tonkinensis collected in China. Their structures were determined to be 11-O-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosylcanthin-6-one, 5-O-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosylcanthin-6-one and 11-hydroxycanthin-6-one-N-oxide, by chemical and spectral methods. In addition, two known alkaloids, canthin-6-one and canthin-6-one-N-oxide, were isolated.