The presence of the alkaloids atropine, hyoscyamine, and particularly the high concentration of hyoscine (scopolamine), which is highly psychoactive, accounts for the widespread medicinal and psychotropic use of Brugmansia and Datura among the American Indians. The proto-Indian Mongoloids who entered the New World during the Late Paleolithic and Mesolithic were unspecialized hunters and gatherers with a shamanistic religion (La Barre, 1972). In addition to the normal experimentation with all types of plants that is inherent in food gathering, the ecstatic-visionary nature of shamanism would have induced the seeking out of plants with psychotropic properties, plants that contained “spirit power”. Datura and Nicotiana were probably among the first plants of this nature encountered by the early Indians, and their usage was widely adopted. It is probable that a knowledge and use of Datura from Mexico and the southwest United States was taken by Indian immigrants into South America. The morphological similarities between the flowers of Datura and Brugmansia, in addition to their similar chemical properties, would have made the latter readily accepted when encountered in the southern continent. Although not so widespread in its usage as tobacco, Brugmansia was known to most of the Indian groups in western South America. Cooper (1949) states that all records of Brugmansia preparations are from the Andean and Pacific fringe of the Continent extending from Colombia to southern Peru and middle Chile. Specifically, he reports its use among the Chibcha and Choco of Colombia; the Quechua of Ecuador, Peru and Bolivia; the Mapuche-Huilliche of Chile; the Zaparo, Jivaro, Canelo and Inga of the upper Amazon; and the Siona, Pioje and Gmagua of the Andean Montana. Since Brugmansia suaveolens is widely used by the Indians of the upper Amazon, it seems probable that this was also true for its lower reaches and in southeastern Brazil; however, no early records make mention of its use. Brugmansia was and is to a lesser extent today valued for both its medicinal and psychotropic properties. It is sometimes difficult to separate these two properties in a shamanistic religion, where there is a characteristic emphasis on malevolent magic and the supernatural as causes of illness, Certain patterns of usage and preparation can be discerned, however, from the older literature and from more modern anthropological and ethnobotanical studies among extant and still viable unacculturated tribes.