To prevent breast cancer-related recurrence and death, adjuvant therapy, including chemotherapy, is given. The decision to deliver chemotherapy requires careful weighing of the risk of toxicity versus the estimated benefit. The risk and benefit are based on information from clinical trials, statistical models, and past clinical experience . Compared to younger patients, it is perceived that older patients have cancers that are lower risk, gain less benefit from chemotherapy, and are at higher risk of toxicity. There is now strong evidence that healthy older women tolerate treatment and stand to gain the same benefits from treatment as do younger women. Numeric age alone, therefore, does not justify withholding adjuvant chemotherapy. New tools to aid in the decision are needed. Fortunately, the expected great increase in the size of the geriatric population spawned the field of geriatric oncology and the development of brief, practical versions of the Comprehensive Geriatric Assessment (CGA) for use in busy oncology clinics are in sight. It is time for us to incorporate elements of the CGA into practice, to systematically identify older patients at substantial risk of toxicity. For frail older women with breast cancer, no therapy or less toxic therapies can be considered, some of which are suggested herein. In addition, as always in oncology, physicians and patients should look for and participate in clinical trials that will define how to treat cancer, especially in older patients, in the future.