Evaluation of functional status plays a unique role in the assessment of older cancer patients. While performance status has been the traditional method for oncologists to assess the impact of a cancer patient's disease, older cancer patients may require a more thorough evaluation of their functional status. Evaluation of functional status provides information that can predict outcomes and may provide information that can be utilized to improve function. Functional status evaluation can be useful throughout the patient's illness, at the initial diagnostic evaluation, for determining appropriate therapies, for the monitoring of therapeutic effect and finally in the palliative phase. There are many different methods available to assess functional status. Individual assessment of functional status in the context of a geriatric assessment may be an important component of the care older cancer patients receive.