A snuff commonly called Epena and used by some South American Indian tribes has been analyzed for its contents of tryptamine derivatives. The powder stems from the Waicas who inhabit the region between the Rio Negro and Rio Branco in North-west Brazil. The active components of the drug are derived from species of Myristicaceae (Virola calophylla Warburg and Virola calophylloidea Markgraf). Epena is used by the natives in divination and diagnosis and treatment of illness. According to available descriptions it causes excitation followed by sedation and sometimes loss of consciousness. Changes in perception during the intoxication include among other things macropsia and possibly parestesia. Because of the interest attached to the central action of tryptamine derivatives in modern psychopharmacological research special attention was focussed on this group of compounds. During the course of the investigation both bioassay and conventional biochemical techniques were used. Eventually it was found, that gaschromatography provided the best means of identification of the components in the alkaloid fraction. The main component of the Epena is 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT). In addition, the drug contains small amounts of N,N-dimethyltryptamine (DMT) and 5-hydroxy-N,Ndimethyltryptamine (Bufotenine). The botanical origin and ethnological use of Epena is discussed especially with regard to the pharmacology of the tryptamine derivatives contained in the powder.