Objectives In the official language of the Inca Empire, Quechua (quichua), which is still the main dialect of many Aboriginal groups in Bolivia, Ecuador and Peru, Ayahuasca is a word composed, on the one hand, of aya which means death, deceased and, by extension, soul, spirit and, on the other hand, huasca which means rope, and, by extension, liana [Bois-Marriage F. Psychotropes 2002;1(8):79–113.]. In recent years, international publications reporting cases of Ayahuasca poisoning appear to be slightly increasing, but are rarely documented analytically, and even more rarely by hair analysis, which is limited to N,N-dimethyltryptamine (DMT) assays. It is in this situation that we propose to report a case of intoxication with Ayahuasca, the repeated use of which is documented by the analysis of hair and nails. Method A 44-year-old woman with a history of recently weaned alcoholism was addressed to the emergency room for mutism and inconsistent speech. It had aboulia, bradykinesia, bradyphemia, as well as auditory and cenesthesic hallucinations (but not visual). The brain scanner showed a fusiform aneurysm at the M2-M3 junction of the right middle brain artery, which, however, did not explain the symptoms. Interrogation of her relatives revealed that she had previously participated in shamanic ceremonies at least three times (the last one that took place 5 days earlier) during which she allegedly consumed Ayahuasca. Biological samples were taken at intake (blood and urine) and 3 days later (30cm brown hair and nail fragments of the hands), before hospitalization in a psychiatric department. These samples were analyzed by CL-SM/SM and CL-SMHR using already published methodologies [Wiart J.F. et al. Int J Legal Med 2020:134:1339–1344] incorporating the use of spectral libraries including a number of toxic (and toxic metabolites) of plant origin [Gish A. et al. Toxicon 2022;210:39–43]. The hair sample was analyzed after segmentation into 2cm sections, except for the last segment (14cm). Targeted analyses were also carried out including research/identification of tryptamines and metabolites by CL-SM/SM. Results Of harmaline, 5-OH-N,N-dimethyltryptamine (5-OH-DMT) and harmine were identified in all samples (including all hair segments). Harmine concentrations are 0.8μg/L, 1.9μg/L, 6.4-93pg/mg and 16.5ng/mg in blood, urine, hair and nails, respectively. DMT was detected in urine (1.4μg/L), hair (2.8-42.4pg/mg) and nails (10 ng/mg), and N-methyltryptamine (NMT) was detected only in urine and nails. Nails and hair have revealed ancient cocaine intakes (distal segments) and more recent alprazolam intakes (proximal segments). Conclusion DMT, 5-OH-DMT and NMT are alkaloids contained in the leaves of Psychotria viridis and related species with hallucinogenic properties. Concomitant use of harmine and harmaline, β-carboline alkaloids contained in Banisteriopsis caapi and possessing inhibitory properties of monoamine oxidases type A, increases and prolongs hallucinogenic activity of DMT. The association of Banisteriopsis caapi and Psychotria viridis (or related species) in the same preparation is named “Ayahuasca”, Hoasca, Daime, and Yage” reported in the traditional pharmacopoeia of South American ethnic groups. These results support the assumptions: (i) recent consumption of Ayahuasca explaining the symptomatology; and (ii) repeated consumption of the beverage in the last months. They also supplement the very rare data in the literature regarding the detection of these substances in the hair and constitute the first data in the nails.