As the toll taken by breast cancer continues unabated, screening programs are widely perceived to play a critical role to improve diagnosis and successful treatment. Breast cancer screening programs are increasingly promoted to women; however, the economic implications of mass screening is a subject of much health policy debate. Cost-effectiveness analysis is an economic methodology widely used to inform such decisions, yet there is a dearth of information available on the economic consequences of mass breast cancer screening. The authors evaluated nine breast cancer screening cost-effectiveness studies that are based on computer simulations, observational trial data, or a combination of both. The results of these studies, conducted in the United States and other countries, indicate that the cost-effectiveness of screening for breast cancer generally compares favorably with other expenditures in the health-care field, although screening younger women does not appear to be as favorable. However, there is considerable variability in the methodology used and a need for more comprehensive research in this area.