The most accurate estimate possible of the number of people infected with the hepatitis C virus (HCV) makes it possible to assess its public health impact and to plan appropriate prevention and care initiatives. Ideally, the estimate of the number of people affected in France should be based on the prevalence rate measured in a random sample of the entire population. Since this method is difficult to implement for logistical, ethical, and financial reasons, a pragmatic approach based on comparing the results of prevalence surveys from the Hepatitis C Concerted Action and other sources of information was adopted. The method used and the results are presented in this article. The estimates presented here are indicative only, as the representativeness of the data from which they are derived cannot be guaranteed. These estimates will need to be validated by other approaches and will be revised as new information becomes available.