Publisher Summary This chapter discusses sex hormones and related compounds, including oral contraceptives. Postmenopausal estrogen deficiency is probably one of the major causes of osteoporosis, besides lack of exercise, low dietary calcium and vitamin D deficiency. Estrogens have been shown to suppress bone resorption, resulting in a diminished urinary calcium excretion. The concept that the addition of progestogens to estrogens might protect postmenopausal patients against endometrial cancer has evoked considerable interest. Side effects of a high-dose estrogen/ progestogen combination therapy during the postmenopause were evaluated in a 10-year, double-blind prospective study. Estradiol valerate, a so-called soft estrogen, is predominantly used for hormone replacement therapy. It depresses plasma gonadotropin levels after daffy doses of 2 mg to an average of 25% for LH and 30% for FSH (30CR). It is quite effective in the relief of hot flushes and causes only moderate proliferation of the endometrium. The effects of tamoxifen on ovarian function in premenopausal women were evaluated. All patients continued to have regular menstrual cycles with biphasic basal body temperature.