Ayahuasca is a psychoactive plant which has been used since immemorial time by tribes of the Amazon basin. It is a part of the traditional medecine of the Amazon and is also considered a plant that teaches human beings. At the beginning of the 20th Century in Brazil, ayahuasca began to be used as a sacrament in a new spiritual doctrine called the Santo Daime. The most recent scientific research shows that ayahuasca is neither toxic nor addictive. It has also been proven that it possesses anti-depressant qualities. In spite of that, its usage is still facing legal problems because it is considered a drug. In an adequate framework, the plant can be beneficial in many ways for Westerners. Firstly, it can be used as an endogenous therapy to render counscious much unconscious psychic material ; secondly, it can be used in psycho-spiritual development ; thirdly, it can function as a safe substitute for toxic and addictive drugs. The present research paper demontrates the results of a 3 month investigation in the Amazon, in the framework of a Master thesis on indigenous and traditional peoples. - Tarapoto in Peru : the Takiwasi Center offers an interesting combination of traditional medecine and Western psychotherapy in the treatment of addictions. - The Valley of Sibundoy in Southern Colombia : the Taita Juan is a traditional healer recognised by the Columbian Ministry of Health. - Mapiá in south-western Brazil : a Community founded by Padrinho Sebastião that uses ayahuasca in a spiritual framework of the Santo Daime tradition. Ayahuasca offers at least two directions for further research : endogeneous therapies and the issue of consciousness outside of the brain.