There is evidence from human studies that estrogen can give rise to health-promoting changes in the vaginal environment in addition to affecting the thickness of the vaginal epithelium. The purpose of the proposed study is to take the first steps in testing the effects of local estrogen treatment on vaginal health parameters in humans. We have chosen an estriol product because, in comparison with estrone (E1) and estradiol (E2), estriol (E3) is generally considered to be a weak estrogen. The duration of estriol's interaction with the estrogen receptor is quick and exhibits rapid metabolic clearance. We have chosen a topical route of administration because it appears to result in fewer systemic effects than oral administration, while allowing us to concentrate treatment locally in the areas we wish to affect.