A retrospective study was performed on a series of 44 patients who had undergone transvaginal ultrasound (US) before hysterectomy. The surgically proved endometrial abnormalities included cystic atrophy, cystic and adenomatous hyperplasia, polyps, and malignancy. The following endometrial findings were evaluated: endometrial thickness, echogenicity, smoothness or irregularity of the contour, definition of the contour, and the presence of cystic areas. Some overlapping features were present between the benign and malignant conditions. Although cystic changes were seen in 76% of benign conditions manifesting with endometrial thickening, cystic changes were also present in 24% of endometrial malignancies. In the majority of endometrial malignancies, the endometrial contour was poorly defined, but 40% of the cases manifested as well-defined endometrial thickening. Most endometrial carcinomas (88%) were either diffusely or partially echogenic, 12% were isoechoic, and there was no endometrial carcinoma that was purely hypoechoic. Although the presence of cystic changes favors a benign condition, malignancy cannot be reliably excluded. Malignancy should be considered in the presence of a poorly defined, irregular endometrium. Transvaginal US has a significant role in the assessment of the endometrium, and although it can help in the differentiation between some benign and malignant conditions, there remain some overlapping features.