PURPOSE OF REVIEW: This review aims to address the important question of the increasing life expectancy and the aging population in the healthcare system today. We try to give some elements that will help the reflection about the ethical stakes balancing the necessity of care in the increasing number of elderly patients and the limited resources available, in the special context of acute care. RECENT FINDINGS: There is growing evidence that the chronological age itself is not a reliable marker of bad prognosis or of mortality. The new concept of frailty may better correlate with the aging process of the elderly. The frailty index is an integrative approach considering the multiple factors impacting on the aging individual. Applied in the practical arena, it might become a useful tool for clinicians. SUMMARY: Aging implies many biological modifications at molecular, cellular, organic levels as well as of the behavior. Some aspects of these processes and their consequences on health are described. The frailty concept is detailed, and its potential interest explained. We conclude that the measurement of aging phenomenon, including the frailty index, may help us to better assess the true health and the required therapeutics of elderly patients.