Breast cancer is among the commonest malignant diseases in women. Over the past two decades tamoxifen has been generally accepted as an endocrine therapy of choice for prevention of breast cancer recurrence. Although tamoxifen was thought to have only a few adverse effects, several reports indicate that it is associated with an increase incidence of proliferative and neoplastic changes in the endometrium, with a 1.3 to 7.5 relative risk of developing endometrial carcinoma. The increased risk of endometrial cancer following the use of tamoxifen has stimulated studies on endometrial diagnostic screening methods. During the past ten years several reports have shown the benefits of transvaginal ultrasonography in detecting endometrial pathologies in patients receiving tamoxifen. Sonohysterography has been claimed to be a useful diagnostic tool on differentiating space-occupying lesion, eg. endometrial polyp, from abnormal endometrial-myometrial junction while the contribution of pulsed flow velocity in diagnosis of endometrial pathologies seems to be inconclusive. More recently a few factors have been identified as risk of developing endometrial cancer after tamoxifen use. These include pre-existing endometrial pathologies, obesity, and prior ERT use. This information provides us a more sensible way in following breast cancer patients receiving tamoxifen. It is proposed here that postmenopausal breast cancer patients intend to have tamoxifen treatment should receive a “two - step evaluation”. The pretreatment evaluation is aimed to classify patients at risk of later development of endometrial pathologies after being exposed to tamoxifen while the ongoing evaluation is designed to closely follow the patents after the initiation of tamoxifen in hope that this will provide a tool for early diagnosis or hopefully a protective measure against endometrial carcinoma associated with tamoxifen therapy.