Dilatation and curettage is used as the ''gold standard'' for diagnosing pathologic endometrial lesions in women with postmenopausal bleeding. In this group of women, about 10% have an endometrial cancer and an additional 20% have some other endometrial abnormality. However, some abnormalities, such as endometrial polyps and submucous fibroids, are difficult to diagnose by dilatation and curettage. In such cases, combining transvaginal sonography with hysteroscopy may be of value. This study compared the use of transvaginal sonography and hysteroscopy for evaluation of the uterine cavity in women with postmenopausal bleeding. The study included 51 women, 39 of whom had an abnormally thick (> 4 mm) endometrium as measured by transvaginal sonography, and 35 of 39 had an abnormal appearance at hysteroscopy. The sensitivity and specificity for the measurement of endometrial thickness using transvaginal sonography to diagnose an endometrial abnormality were 100% and 75%, respectively. The corresponding figures for hysteroscopy were 97% and 88%. In all women with an endometrial thickness of 8 mm as measured by transvaginal sonography, hysteroscopy is identified as an abnormality. The study indicates that transvaginal sonography reveals an endometrial thickness of greater than or equal to 8 mm and the histopathologic diagnosis after dilatation and curettage is atrophic endometrium, hysteroscopy will probably reveal an endometrial polyp or submucous myoma.