Promestriene (3-propyl ethyl, 17B-methyl estradiol) is a synthetic estrogen analog, which is used in topical estrogen therapy. Promestriene’s potential for treating vaginal atrophy symptoms associated with aromatase inhibitor treatment would be precluded if its minimal absorption leads to estrogen-like effects on cell proliferation and estrogen-responsive gene expression. The concern with absorbed vaginal estrogens or estrogen analogs is that they activate occult sites of residual breast cancer or negate the tumor suppressive effects of aromatase inhibitor adjuvant therapy. Promestriene has been studied in phase IV of the clinical trial on improvement of hormonal cytology, local and systemic climacteric complaints, as well as its endometrial security in patients with vaginitis atrophic pelvic; organ prolapse and endometrial hyperplasia. It has been also studied in phase III of the clinical trial in the post-operative patients with hypospadias. In addition, promestriene was in phase IV of the clinical trial to study its treatment of patients with vaginosis, bacterial, but that studied was terminated.