This study is a preliminary reflection on the ritual appropriation of ayahuasca, an Amazonian psychoactive ritual substance, by members of a Guarani Indian village on the southern coast of Santa Catarina. Their shamanic leaders have adapted the use of this beverage into their ritual practices, and recognize it as part of their culture and tradition. This process of appropriation is a result of the formation of a network of relations that involves various actors, among them the Guarani Indians, members of an international spiritual group, those of the Brazilian ayahuasca religion, Santo Daime and medical personnel contracted by the Federal Government. Based on this case study, we propose that shamanism today often emerges out of specific political and historical contexts and in many cases should be thought of as a dialogical category, constructed through the interaction between actors of different origins, discourses and interests.