This thesis highlights the use of indigenous medicine by physicians in the urban areas of Colombia. Traditional healing practices from the cultural area of the Amazon, in particular the ritual use of the ayahuasca-concoction, have spread out since the 1990s. On the basis of five case studies, different forms of co-operation between indigenous healers and scientifically trained physicians are described and compared. The qualitative content analysis of 21 interviews with patients display their motivation of the utilization of indigenous medicine as well as subjective ritual experiences and effects on health and daily life. Indigenous medicine is being used as an additional therapeutic option beside academic and complementary medicine. During the rituals patients generally experience altered states of consciousness with a high degree of self-reflection and undergo experiences of cleansing and catharsis. Stated long-term effects include improved psychological well-being, better coping strategies and behavioural changes.