DES is an estrogen; specifically, it is a highly potent full agonist of both of the estrogen receptors (ERs). It has approximately 468% and 295% of the affinity of estradiol at the ERα and ERβ, respectively. However, EC50 values of 0.18 nM and 0.06 nM of DES for the ERα and ERβ, respectively, have been reported, suggesting, in spite of its binding affinity for the two receptors, several-fold preference for activation of the ERβ over the ERα. In addition to the nuclear ERs, DES is an agonist of the G protein-coupled estrogen receptor (GPER), albeit with relatively low affinity (~1,000 nM). DES produces all of the same biological effects attributed to natural estrogens like estradiol. This includes effects in the uterus, vagina, mammary glands, pituitary gland, and other tissues.