The preservation of naturally mummified bodies in the Nazca drainage and Yauca Valley provided an oppor­tunity to analyse for the first time which of the psychoactive plants were used on the southern Peruvian coast. Toxicological analysis allows us to better understand the ancient medicine, trade network and religiosity of the region of interest. Hair samples of 22 individuals (including four trophy heads) were examined using LC-MS/MS for the presence of coca alkaloids and metabolites (cocaine, benzoylecgonine, cocaethylene), mescaline, trypt­amine, harmaline, and harmine. LC–MS/MS was performed using electrospray ionization (ESI) in the positive mode, multiple reaction monitoring, and a deuterated internal standard (Diazepam-D5). The limits of quanti­fication achieved for analytes were from 1 to 5 ng/g. Recoveries ranged from 91,6 to 113,7%. The method demonstrated an intraday and interday precision CV of <15%.