The cost of educating a medical student has been an issue of intermittent public concern for most of the twentieth century, beginning in 1910 with the Flexner Report. The issue is now reemerging as a topic of high public and political interest, for several reasons, including concern about medical schools and their financing. Estimates of medical student education costs appear to vary widely; but such variations derive from the different ways the question has been framed. Costs can be categorized as instructional costs and total educational resource costs. Instructional costs, which can be distinguished further as marginal costs or proportionate-share costs, are those costs that can be related directly to the teaching program and its support. Total educational resource costs are those costs supporting all faculty deemed necessary to conduct undergraduate medical education in all their activities of teaching, research, scholarship, and patient care. The authors review studies spanning a period of more than 20 years and find that instructional cost estimates of medical student education, when adjusted to a standard base year (1996 dollars), fall within a fairly narrow range: most are between $40,000 and $50,000 per student per year. Estimates of total educational resource costs show greater variation, but four of six estimates fall between approximately $72,000 and $93,000 per student per year. The authors note that present directions of curricular innovation-small-group learning, investment in information technology, and clinical education in ambulatory sites-offer little solace to those concerned with mitigating the costs of medical student education. Several proposals have been advanced to restructure medical student education in the name of efficiency and cost-effectiveness, but many are simply maneuvers to transfer responsibility for costs to other entities. Only by a net reduction of the medical school curriculum might costs truly be reduced. Yet the medical knowledge base continues to increase, as does the range of information and skills required of medical students. Unless society is prepared to change dramatically its concept of the well-educated physician, opportunities for significant reductions in the costs of medical student education are difficult to visualize.