Many Indian tribes in the northwestern parts of the Amazon Valley and of the headwater regions of the Orinoco drainage-basin utilize preparations of the bark resin of several species of Virola either as a snuff or orally in witchcraft and medicine. Indeed, certain very primitive tribes simply ingest the resin directly, with apparently no preparation, for its psychoactive effects. Of the species indicated as sources of the narcotic paste by these Boras and Witotos, Virola calophylla, V. elongate, V. peruviana, V. venosa (Benth.) Warb. (or a closely related species) could, on the basis of their chemical constitution, be so used. Material from the same trees from which the natives took bark, and frequently also the paste which they prepared from the bark, were analyzed on the laboratory ship Alpha-Helix shortly after collection. V. calophylla contained N,N-dimethyltryptamine and N-monomethyltryptamine; V. elongata yielded tryptamine, N-monomethyltryptamine, N,Ndimethyltryptamine, 5-methoxy-N,N-dimethyltryptamine and 5-methoxy-Nmonomethyltryptamine; and V. peruviana showed N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine. What has been identified tentatively as V. venosa vel aff. - but which may represent a new species allied to V. venosa - was collected only in a sterile condition: tests indicated that it contains N,N-dimethyltryptamine, N-monomethyltryptamine, 5-methoxyN,N-dimethyltryptamine and 5-methoxy-N-monomethyltryptamine (Holmstedt, Lindgren, Rivier and Schultes, unpublished data). The possibility of the use of Virola peruviana - previously reported as a source of the hallucinogenic snuff va-hee in the Colombian Vaupes (Lai, TinWa, Mika, Persinos and Farnsworth, 1973) - has, as indicated above, been substantiated on the basis of chemical examination of material referrible to this species. These studies indicate how rapidly and effectively aboriginal traits can disappear from a culture. It is a lesson in our race to learn as much as possible of the ethnopharmacology of the northwest Amazon before complete acculturation and/or extinction of tribal groups occurs.