Hepatitis C infection is an emerging problem in public health and is now the most common blood-borne infection. The virus imposes a significant personal and social burden on those infected, as well as substantial costs to the health care system. In this paper we report an estimate of the costs of hepatitis C and consider the role such information might play in determining an appropriate preventive strategy. Preventing a single case of HCV would release resources valued Aus $6000 and Aus $19,000, depending on whether production loses were included. This information can be used to derive cost-effectiveness thresholds for any preventive activity, but is not in itself necessary in determining health priorities. Information on the marginal cost-effectiveness of preventive methods is both necessary and sufficient.