In this report we evaluated the action of conjugated equine estrogens (CEE) on vaginal symptoms, cytology, pH, and flora in late postmenopausal women without any previous hormone therapy. The study was a randomized, double-blind, placebo-controlled trial with 48 late postmenopausal women who received placebo or unopposed CEE (0.625mg/day of CEE orally) during three months of treatment. Vaginal and sexual complaints were evaluated through daily diary cards. We analyzed vaginal changes through cytology and pH measurements. After three months of treatment, 20% of placebo-treated patients and 80% of the CEE-treated patients reported improvement in vaginal dryness and irritation. In the latter group, the vaginal cells and Lactobacillus increased and the vaginal pH decreased, without other changes in sexual complaints. We concluded that estrogen ameliorated the genital tract of late postmenopausal women without any previous hormone therapy.