Hepatitis C is a global health problem caused by infection with the hepatitis C virus. Although representative prevalence data are not available from many countries, available data indicate that approximately 3% of the world's population is infected with HCV. It is estimated that as many as 170 million persons world-wide may be infected with HCV. In many countries, the exact magnitude of the problem and the relative contribution of the various routes of transmission have not been defined with population-based studies. Wherever possible such studies should be performed to enable countries to estimate the burden of hepatitis C disease, to prioritize their preventative measures and to make the most appropriate use of available resources. To assess hepatitis C on a global scale, the World Health Organization (WHO) organized a consultation of international experts, in order to review the public health aspects related to hepatitis C infection and to make recommendations for its prevention and control.