In this paper, the author discusses the different cultural sequences which have occurred over the last two decades in the consumption of xono (Banisteria caapi) among the Chama. The Chama are an aboriginal group who belong to the Takoma linguistic family and live in the Peruvian-Bolivian Amazon River area. They have undergone many cultural changes and these changes have produced variations in the use and symbolic meaning of xono. The author describes the botanical and pharmacological components of xono and discusses the psychological effects of its use. In the author’s view, mescaline is the archetypal example of drugs of this kind and can be considered as a model with which other drug use can be compared. There have been three patterns of consumption of xono among the Chama. In the earliest pattern, which the author calls sacramental, the Chama integrated use of xono into the general culture. In 1942 Metraux noted that the Chama did not use alcoholic beverages or hallucinogenic drugs. However, by 1956 the Chama had two different ritual ceremonies involving xono: communal and shamanic. In communal usage the entire community took part in the ceremony through a complex set of ritual procedures. In shamanic consumption, usage, only specific groups of people, such as hunters, soldiers, or sick people took part. The Chama believe that the xono power was given to a Peruvian by two mythical heroes, Kosiexa and Mesi. These heroes are believed to have become transformed and to have taken the shape of the Sun and the Moon. For the Chama, xono was an expression of edoxkiana (respect). A Chama who participated in the xono cult was believed to have changed his nature and to have participated in the nature of the spirits. It was this change which gave him power. However, it was felt that the procedures for use of the drug had to be strictly followed or the person would become critically ill and die. The author argues that this first stage in the use of xono symbolizes the search for an ontological change by the acquisition of sacred power through the effects of xono. The second pattern was that of annihilating consumption. After the 1963-67 war which occurred between several small Chama groups, xono use changed. It was no longer consumed in community ceremonies which involved widespread symbolic and religious motivation, but was consumed privately, without rituals, and only by survived. dealt with war between the two souls which the Chama believe each person possesses. One, ekuilcia, is believed to be attached to the body while the other, exosaxawa, can separate from the body during shamanic trance, dreams, and at death when it goes to the sacred lake. Larraya suggests that this use of xono symbolizes the fight between life and death which is also represented by the two souls. The third pattern, apocalyptic consumption, developed after Christian beliefs began to have an affect on the Chama, roughly around 1960. Under Christian influence xono took on a new meaning, becoming a symbol of evil and a terrible sin against the new god. The evangelization of the Chama led to a suppression of xono for tribal cult use; its use was confined to shamanic rites and came to represent a serious transgression against the beliefs of the new religion. It is now associated with ideas of apocalyptic catastrophe. In a previous paper (see Transcultural Psychiatric Research Review 14 ( 1977 ) : 106-08 ) the author describes the same theory of the three consumption models, this time as applied to alcohol drinking roles among the Chaco aborigines of Bolivia.