A chemical investigation of the roots of Mimosa ophthalmocentra, carried out in our laboratory, with the aim of monitoring the possible hallucinogenic activity, led to isolation and identification of three alkylamines (N,N-dimethyltryptamine, N-methyltryptamine and hordenine). The results explain the traditional use of this plant by several tribes in northeast Brazil to prepare a potent hallucinogenic drink in mystic-religious ceremonies.