A new triterpenoid glycoside containing an amino sugar moiety has been isolated from Pithecellobium cubense and P. arboreum and identified as O(3)-(2-acetylamino-2-deoxy-β-D-glucopyranosyl)-oleanolic acid. β-D-Glucopyranosyl-α-spinasterol was also obtained from P. cubense. A new triterpenoid glycoside has been isolated from Pithecellobium cubense Bisse and P. arboreum (L.) Urban. While both the electron impact (EI) and the electron attachment (EA) mass spectra only showed peaks corresponding to a triterpenoid hydroxy acid of the α- or β-amyrin series, the spectra of the acetyl derivative in addition indicated an amino-deoxyhexosyl moiety (see Experimental). The ¹³C NMR spectrum (Table 1) was in agreement with the structure O(3)-(2-acetylamino-2-deoxy-β-glucopyranosyl)-oleanolic acid. The IR spectrum showed the N-acetyl group. This structure was confirmed by hydrolysis to oleanolic acid and 2-amino-2-deoxy-α-D-glucose hydrochloride. The negative molecular rotation difference between the glycoside and its aglycone (Δ[M], -75° in pyridine) proved the β-configuration of the glycoside ([M] of methyl 2-acetylamino-2-deoxy-β-D-glucopyranoside -111° in water, of the α-D-isomer +308° in water). This assignment was confirmed by the ¹H NMR spectrum (J₁,,₂, = 8 Hz). The new compound is the first natural triterpenoid glycoside containing an amino sugar moiety. β-D-Glucopyranosyl-α-spinasterol was also isolated from P. cubense.