Elderly subjects are persons over the age of 65. Advancing age may place them at increased physical, cognitive, or financial risks. However, there is no specific age at which persons become high risk subjects and thereby ineligible for research. Researchers have the responsibility to determine the level of risk that research poses on an individual basis and to minimize risks accordingly. The use of age per se to define the ability to consent and therefore to participate in research is not valid , and the inclusion of older persons in the research enterprise is important. When older persons are cognitively impaired or institutionalized, the same protections apply to them that apply to persons with cognitive or emotional impairments and to children. They should not be used as subjects merely because they provide a convenient sample, but research involving elderly institutionalized persons should bear some direct relationship to their condition or circumstances. Furthermore, they should be informed and given the opportunity to assent to research, to the extent they are able, even if a guardian must provide informed consent for them to be subjects.