Alpha Ethyltryptamineis a psychedelic, stimulant and entactogen of the tryptamine chemical class.Originally believed to exert its effects predominantly via monoamine oxidase inhibition, alpha-ethyltryptamine was developed as an antidepressant by Upjohn chemical company in the United States under the name "Monase" but was withdrawn from potential commercial use due to an unacceptable incidence of agranulocytosis.

αET is structurally and pharmacologically related to α-methyltryptamine (αMT), but its effects are slightly different. In contrast to αMT, αET is less stimulating and hallucinogenic, its effects resembling more those of entactogens like MDMA ("Ecstasy").Similarly to MDMA, αET has been demonstrated to be a releasing agent of serotonin, norepinephrine and dopamine; in addition, it acts as a non-selective serotonin receptor agonist.