From the fruits of Alangium lamarckii, three new tetrahydroisoquinoline-monoterpene glucosides, isoalangiside, 3-O-demethyl-2-O-methylisoalangiside and methylisoalangiside, were isolated. Their structures were determined by spectroscopic and chemical methods. This is the first instance of the isolation of glucosides with the same absolute configurations as deacetylisoipecoside, and strongly supports the intermediacy of the latter compound in ipecac alkaloid biosynthesis.