We report the case of a young woman who indicates she was victim of sexual assault after drinking ayahuasca, a beverage originate from South America with hallucinogenic properties. After ingestion of ayahuasca, the complainant stated that she was in a state of unconsciousness incapable to resist her aggressor. The drink of interest was seized by the police, and a hair sample of the victim was collected 3.5 months after the offence. The specific dosage of the main active components in the ayahuasca beverage (harmine, harmaline and DMT) and the hair sample (3 segments) were performed by liquid chromatography coupled with triple quadripole tandem-mass spectrometry. The concentrations of harmine, harmaline and DMT found in the hair segment covering the period of the offence were respectively 137, 101 and 33 pg/mg. The concentrations measured in the drink were respectively 1, 0.3 and 2.8 mg/mL. Hair analysis allowed to confirm the reality of exposure to ayahuasca. To our knowledge, it is the first report documented by hair analysis of a case of drug-facilitated crime, which could be named ‘‘chemical vulnerability’’ because the victim consumed the ayahuasca beverage willingly. Besides the traditional setting of shamanism, it has been used for several decades, it is clearly orientated towards movements dealing with spiritual development and neo-shamanism, which can lead to excesses because of the important psychoactive effects of ayahuasca.