<h3>Study Objective</h3> Compare the ultrasonography and the hysteroscopy findings in asymptomatic postmenopausal patients showing endometrial thickening. <h3>Design</h3> Observational study (Canadian Task Force Classification II-2). <h3>Setting</h3> San Salvatore Hospital of L'Aquila, Department of Obstetrics and Gynecology. <h3>Patients or Participants</h3> 315 asymptomatic postmenopausal women with endometrial thickening >4 mm. <h3>Interventions</h3> Diagnostic hysteroscopy, endometrial biopsy. <h3>Measurements and Main Results</h3> That patients had normal endometrium (8.6%), atrophic endometrium (26.7%), single benign polyp (47.6%), multiple polyps (8.6%), myoma (1.9%), focal hyperplasia (3.8%), diffuse hyperplasia (0.9%) and endometrial carcinoma (1.9%). In 30 women under therapy for breast cancer (thickening >5 mm) the hysteroscopic exam showed normal endometrium (50%), multiple polyps (20%), focal hyperplasia (20%) and diffuse hyperplasia (10%). For this subcategory of patients, the histopathological analysis confirmed the hysteroscopic diagnosis in 100% of case. It is not statistically valid to give to the homogeneity data of the endometrial thickening a direct association with the suspicion of polyp, as well as the ascription of a direct association with all the other suspicions except polyp to a non-homogeneous thickening cannot be considered statistically valid. The ROC analysis shows that the best cut-off for suspected polyp in ultrasonography is ≤6 mm (sensibility of just 66.0%, specificity of just 58.18%). By the ROC analysis, an 8 mm cut-off of ultrasound thickness was identified, above which the suspicion of endometrial carcinoma is strongly solid (specificity of 84.47% and a sensibility of 100%). <h3>Conclusion</h3> Hysteroscopy has a positive predictive value (PPV) of 100%and a negative predictive value (NPV) of 97.952% in detecting a risk of malignancy, with a specificity of 100% and a sensibility of 77.78%, demonstrating that hysteroscopy is the gold standard for the diagnosis of malignant endometrial pathology or an endometrial condition at severe risk of malignancy. A direct endoscopic exam is the only valid exam in the diagnosis of the intracavitary pathologies, especially in asymptomatic postmenopausal patients.