Over the last 30 years, a number of genetic and environmental factors that lead to decreased length of life have been identified. Unfortunately, much less progress has been achieved in identifying genes associated with longevity that protect from common diseases or slow the aging process. Recent compelling evidence supports a role for important genetic and environmental interactions on longevity in lower organisms. Although less is known in humans, commonality in molecular and biological processes, evolutionary arguments, and epidemiological data would strongly suggest that similar mechanisms also apply. The completion of the Human Genome Project and the rapid innovations in technology will make possible the identification of human longevity-assurance genes. This article reviews such evidence, its implications for the identification of human longevity-assurance genes, and the significance of finding longevity genes to human health and disease.