3-Methylmethcathinone (also known as 3-MMC or metaphedrone^[1]) is a novel stimulant–entactogen substance of the cathinone class. It is a structural analog of mephedrone (4-MMC). It is thought to produce its effects by promoting the release of dopamine and serotonin, although studies are lacking.

3-MMC first became available on the online research chemical market shortly after the banning of mephedrone. It is a prominent example of a contemporary designer drug specifically chosen to mimic and/or replace the functional and structural features of its recently-controlled predecessors.