Background: Tamoxifen (TMX) currently regarded as the standard treatment for breast cancer (BC) patients‎, however in recent years, several researchers reported gynecological side effects and attributed them to TMX and its estrogenic (ER) effects. We evaluate the side effects of TMX on female ‎endometrium and ovaries. Methods: an ultrasound-based cohort study conducted in three oncology centers. The studied groups included a total of ‎‎255 patients, 140 premenopausal (PreM) and 115 postmenopausal (PostM) female patients with ER-positive BC using TMX adjuvant hormonal treatment in ‎a dose of 20 mg/day for at least three months after surgery and adjuvant ‎chemo/radiotherapy.‎ The study conducted at the three main oncology centers in Baghdad. The collected data includes: age of the patient, menopausal status, co-morbid chronic illness such as hypertension, diabetes mellitus, etc, and used medications.