A new C(19)-quassinoid-type glycoside has been isolated from the roots of Eurycoma longifolia. The structure elucidation of the compound was achieved by a combination of one- and two-dimensional NMR techniques, including (1)H-(1)H-correlation spectroscopy (COSY), (1)H-(13)C-heteronuclear correlation spectroscopy (HMQC), and (1)H-(13)C-heteronuclear multiple-bond correlation spectroscopy (HMBC), as well as high resolution electrospray ionization Fourier transformation mass spectrometry (HR-ESI-FT-MS) data. The C(1)-glycosidation site in the quassinoid framework is encountered for the first time.