An estimated four million individuals in the United States have Alzheimer's disease (AD). This number is expected to more than triple by mid-century. Primary care physicians have a key role in evaluating older patients for early signs of dementia and in initiating treatment that can significantly retard its progression over the maximum period of time. That role and its challenges will inevitably grow along with the expected increase in the population aged 65 and older. The tendency for physicians to dismiss memory complaints as normal aging must be replaced by awareness of the need to assess and possibly intervene. Early intervention is the optimal strategy, not only because the patient's level of function will be preserved for a longer period, but also because community-dwelling patients with AD incur less societal cost than those who require long-term institutional placement. Institutionalization contributes heavily to the annual cost of care for AD in the United States, which is estimated to be $100 billion annually.