As the average lifespan in Western countries continues to expand, health care for the aged has become an increasingly important research focus. While clinicians and vertebrate researchers have frequently concentrated on specific age-related diseases, particularly neurodegenerative diseases such as Alzheimer's and Parkinson's Diseases, researchers working with invertebrate genetic model systems have gained important insights into global mechanisms of lifespan determination. Still others have employed biochemical and molecular approaches to elucidate processes contributing to common diseases of the elderly, such as cancer and diabetes. In between the broad focus on organismal aging and the more narrow focus on cellular dysfunction is the study of aging at the level of individual organ function. This review will attempt to highlight recent advances in the area of age-related deterioration of organ function provided by the use of transgenic model organisms, with a view toward incorporating these observations into a framework provided by both broader theories of the aging process and studies of cellular function during aging.