The aim of this study was to assess the ability of transvaginal sonography (TVS) and office hysteroscopy with sharp curettage to characterize the morphological changes in the uteri of asymptomatic postmenopausal women taking long-term tamoxifen for breast cancer. The overall acceptability of a single-visit screening clinic for these women was also evaluated. Fifty-eight women were recruited from patients undergoing regular follow-up at the Leicester Royal Infirmary for breast cancer. A single-visit clinic was acceptable to 94.8% of these women. Transvaginal sonography detected endometrial thickness of greater than 5 mm in 84.5% of cases, but there was no relationship between total tamoxifen exposure and endometrial thickness. Transvaginal sonography also detected uterine lesions such as fibroids and endometrial cysts in 34.5% of cases. Hysteroscopy detected the latter uterine lesions in 53.4% of cases, with three cases (5.2%) of endometrial polyps also being identified in these women. Sharp curettage sampling of the endometrium produced specimens sufficient for diagnosis in 84.5% of cases; 70.7% of specimens were reported as showing types of 'quiescent' endometrium with 13.8% of specimens showing 'active' endometrium. In the latter group, there was a case of complex hyperplasia detected and also a case with granulomatous endometritis. For each histopathological diagnosis identified, there was a wide range of endometrial thickness recorded by TVS. A single-visit screening clinic involving TVS and hysteroscopy with sharp curettage was acceptable to asymptomatic women taking tamoxifen. However, hysteroscopy was more effective than TVS in detecting endometrial lesions such as polyps, fibroids and cystic areas. Although TVS detected endometrial thickness greater than 5 mm in the majority of cases, there were no malignancies detected and, for each histopathological classification, there was a wide range of endometrial thickness associated. Thus, the isolated use of TVS is insufficient for screening the endometria of these women.