Miroestrol is a phytoestrogen, a plant-derived chemical that mimics the biological activity of the hormone estrogen.

Miroestrol was first reportedly isolated from the Thai herb Pueraria mirifica in 1960 and thought to be responsible for the supposed rejuvenating properties of the plant.

[1] However, more recent studies have suggested that the active ingredient may actually be the closely related chemical compound deoxymiroestrol (shown below), and the reported presence of miroestrol may only have been an artifact of the isolation procedure.

[3] Because of their estrogenic activities, miroestrol, deoxymiroestrol, and other related compounds have been the targets of scientific research including total synthesis.

Extracts of Pueraria mirifica reportedly containing miroestrol are marketed as dietary supplements intended to lead to breast enhancement in women.