Ospemifene is a selective estrogen receptor modulator (SERM), a metabolite of toremifene, with a unique estrogen agonist/antagonist tissue profile. Ospemifene was recently approved in the US for the treatment of dyspareunia associated with vulvar and vaginal atrophy in postmenopausal women, and is being investigated for the treatment and prevention of osteoporosis and breast cancer. Ospemifene binds ERα and ERβ with approximately equal affinities with IC50 values for estrogen receptor (ER) α and β of 0.8 µM and 1.7 µM, respectively. Ospemifene has estrogen-like effects on the vaginal epithelium and bone, antiproliferative effects in breast, and a neutral endometrial profile.