The major role of ultrasound in the evaluation of abnormal uterine bleeding, other than that occurring during pregnancy, is in postmenopausal women. Because postmenopausal bleeding can be the presenting symptom of endometrial cancer, any woman with this symptom should be evaluated to diagnose or exclude carcinoma. Over the last two decades, the role of ultrasound in the evaluation of postmenopausal bleeding has changed markedly, from little or no role in 1990 to a major role today. In the intervening years, numerous studies have shown that ultrasound is at least as sensitive as endometrial biopsy for endometrial cancer and that ultrasound can reliably exclude cancer without the need for biopsy in some women with postmenopausal bleeding. In particular, numerous studies have shown that women with an endometrial thickness of 4 mm or less have an extremely low likelihood of endometrial cancer and thus do not need to undergo endometrial biopsy. Ultrasound can also help in the selection of an appropriate biopsy technique. In a woman with postmenopausal bleeding and a thick endometrium, a sonohysterogram can determine whether the endometrium is diffusely thick or has focal areas of thickening. With diffuse thickening, a blind endometrial biopsy is appropriate. When there are one or more focal areas of thickening, hysteroscopic biopsy is likely to be the better choice. We present two clinical algorithms, either of which is an acceptable approach to the use of ultrasound and/or endometrial biopsy in women with postmenopausal bleeding: the "ultrasound-first" approach and the "biopsy-first" approach.