Since the prevalence of many chronic health conditions increases with age, we might anticipate that as the population ages the proportion with one or more such conditions, and the cost of treatment, would rise. How much would the overall prevalence of chronic conditions increase in a quarter century if age-specific rates of prevalence did not change? How much would the requirements for health care resources increase? How much difference would it make to those requirements if people had fewer chronic conditions? The overall prevalence rates for almost all conditions associated mostly with old age would rise by more than 25 per cent, and health care requirements would grow more rapidly than the population - more than twice as rapidly in the case of hospital stays - if the rates for each age group remained constant. Even modest reductions in the average number of conditions at each age could result in substantial savings.