Tamoxifen and Raloxifene are Selective Estrogen Receptor Modulators (SERM). Tamoxifen is used in the treatment of metastatic breast cancer after mastectomy or radiation therapy. It competes with estrogen for binding with estrogen receptors in the breast tissue. Raloxifene is used as prevention and treatment of osteoporosis in post-menopausal women. It acts as an estrogen agonist in bone, leading to decreased bone resorption, increased bone density, and decreased vertebral fractures. Unlike Tamoxifene, Raloxifene does not have appreciable estrogen receptor agonist activity in the endometrium and therefore does not predispose to endometrial cancer. Raloxifene decreases serum total cholesterol and LDL. Tamoxifen causes hot flashes and nausea.