Raloxifene is a selective estrogen receptor-modulating agent that has been recently approved by the FDA for the treatment of osteoporosis in postmenopausal patients. A phase II trial evaluating the safety and efficacy of raloxifene in premenopausal patients at high risk for developing breast cancer has been recently approved by the IRB (98-C-0123). In this protocol, for assessment of the effects of raloxifene on the endometrium and ovaries, patients are scheduled to be studied with transvaginal sonography and hysterosonography, once during their menstrual cycle at periodic intervals. They are also scheduled to have endometrial biopsies as indicated. It is known that all SERMs (clomiphene, tamoxifen and in one small study raloxifene) raise the area under the curve of estradiol levels throughout the cycle in premenopausal women. Our study is designed to study the reproductive effects of raloxifene in these young women with competent ovaries using sonography of the ovaries and endometrium, and correlating it with steroid hormone levels which would be obtained under protocol 98-C-0123.