5-Methylethylone (5-methyl-βk-MDEA, 5ME) is an empathogen, stimulant and psychedelic drug of the amphetamine, phenethylamine, and cathinone chemical classes. It is structurally related to ethylone, a novel designer drug. Relatively little data exists about the pharmacological properties, metabolism, and toxicity of 5-methylethylone, though it has been sold as a designer drug.

5-Methylethylone is unscheduled in the United States, but it is not currently approved by the Food and Drug Administration for human consumption. The state of Vermont lists it as a regulated drug.