Over the last 30 years, the elderly population of developed countries has shown an unprecedented increase. This process has raised alarm about the future affordability of health care systems. In this context, we consider the effects of population aging on health care expenditure within a process involving several elements: the increasing number of elderly persons, variations in the health status of the elderly and the evolution of the cost of medical treatment. The main conclusion is that only a small part of the increase in expenditure is due to population aging. Furthermore, because the average health status of the elderly has improved with greater longevity, we suggest that most of the increase in health care expenditure can be attributed to the evolution of non-demographic factors. Such as health services utilization, treatment cost and the development of new medical technology. Unlike populations aging, these factors can be subjected to future regulation and consequently, can to a large extent be controlled.