Estradiol 17-β, the primary estrogenic hormone elaborated by the human ovary, though available in pure form, has not been used extensively in oral menopausal therapy because it is considered ineffectual due to poor gastrointestinal absorption. Other estrogen preparations in current clinical use are effective orally but are attended by drawbacks such as unpleasant side effects, high cost or suspected thromboembolic risk. A new dosage form of pure 17-β Estradiol, micronized for better absorption, was not only well tolerated but also clinically effective in this preliminary study of menopausal therapy.