Mammographic screening for breast cancer in cognitively impaired women poses significant ethical questions. Many woman with dementia should not be screened because of the greater harm than benefits and the difficulty in obtaining informed consent. This article reviews the current controversy about mammography and then suggests a risk/benefit analysis for this vulnerable population. Autonomy, decision-making capacity, and the roles of surrogates and physicians are considered, as are ageism and the risk of undertreatment. The harm of overdiagnosis and subsequent overtreatment for women who are cognitively impaired, have comorbidity and a limited life span are outlined. In these cases, the burdens of mammography outweigh the benefits. For women with early cognitive impairment and longer life expectancies, the potential benefits may outweigh the harms. A decision-making process by the patient, proxy, and practitioner that takes account of foreseeable risks and benefits, patient capacity and preferences, and the effect of this screening intervention on quality of life is outlined.