Helle Kaasik University of Tartu, Estonia + University of Campinas, Brazil Varieties of chemical composition of Ayahuasca Abstract: Ayahuasca is an entheogenic brew made from Amazonian vine Banisteriopsis caapi, often with admixture plants containing psychedelic N,N-dimethyltryptamine (DMT). Ayahuasca is highly variable in its appearance, taste, effects and chemical composition. We analyzed 102 samples of ayahuasca from different locations (mostly Europe and Brazil) and traditions (indigenous “shamanism”, neoshamanism and Santo Daime). Concentrations of DMT, tetrahydroharmine (THH), harmine and harmaline in the samples were determined by high performance liquid chromatography and mass spectrometry at the University of Campinas, Brazil. Interesting tendencies emerged according to the traditions where the samples came from. Indigenous brews showed a strong linear relationship between concentrations of N,N-dimethyltryptamine (DMT) and tetrahydroharmine (THH), forming a well-ordered line in the scatterplot of ratios of concentrations of THH and DMT to the concentration of harmine. In terms of the psychoactive effect, this correlation can be interpreted as carefully balancing the psychedelic visionary intensity of DMT with the support and afterglow of THH. Samples from ayahuasca religion Santo Daime followed this traditional line of balance with some scattering around it, preferentially towards increased concentrations of DMT. Samples from various “neoshamanic” facilitators formed a scattered cloud with outliers further towards increased concentrations of DMT, and contained in average 48% more DMT than indigenous brews. No significant correlation between concentrations of DMT and THH was seen among the neoshamanic samples. From Europe we found even fake “ayahuasca” concocted from moclobemide, Mimosa tenuiflora and psilocin. Conclusions: Not all ayahuasca is the same. “Outliers” are out there. Know well what you drink.