Ayahuasca is a mix of psychoactive substances from the Amazon, popularized in recent decades by transnational religious networks, and academic researchers interested in its clinical applications. The current dissertation is a study of ayahuasca rituals in Catalonia and surrounding areas, focusing on its use in the treatment of addictions. The main objectives of the research are: a) to use the perspective of medical anthropology to understand informal ayahuasca social networks as being embedded in alternative health care systems; b) to explain the academic interest in ayahuasca because of the relations and tensions between science and religion/spirituality; c) to gain a cognitive and cultural understanding of how the healing ritual works in the case of ayahuasca being used to treat addictions. The research studies several centers in Catalonia, Valencia, and the Balearic Islands, using an ethnographic approach that includes interviews with the leaders of the groups, participant observation for the analysis of the ritual design in each center, and biographic techniques for the study of cases of addicts who have been treated and cured. Ritual healing will be investigated using a medical anthropology model and an interdisciplinary approach that considers both cultural and cognitive elements.