Objectives: A prospective caseucontrol study was carried out to assess the value of elastosonography in identifying endometrial pathology in women using Tamoxifen (TAM) for breast cancer. Materials and Methods: In total, 66 women using TAM for breast cancer were enrolled for the study with 61 premenopausal and 61 postmenopausal healthy controls. Ultrasonographic findings (strain ratio, endometrial thickness) were evaluated in regard to the duration of TAM usage, histopathological findings, and menopausal status. Results: Patients with endometrial cancer (EC) and cystic endometrial hyperplasia (CEH) were found to have longer duration of TAM usage, increased endometrial thickness, and higher strain ratios compared with controls. A significant positive correlation was found between duration of TAM usage, endometrial thickness, and the strain ratios. Endometrial thickness and the strain ratios were significant predictors for groups under risk. Cutoff values for endometrial thickness, strain ratios, and duration of TAM usage were 12.55 mm, 2.46, and 18 months in premenopausal group and 7.75 mm, 7.70, and 32 months in postmenopausal group to predict risky population, respectively. Conclusion: Endometrial tissue strain ratio was found to be significantly increased in cases with endometrial pathologies. Addition of elastosonography modality to B-mode may improve the diagnostic accuracy during the follow-up of women using TAM for breast cancer.