Although a lot of novel information and data on the epidemiology of hepatitis C virus (HCV) infection are available worldwide, the majority of these information are often fragmentary and sometimes contradictory. This review tries to highlight all the data available on the prevalence (i.e. the number of cases present in a known population), the risk factors, the natural history and the incidence (i.e. the number of new cases that occur every year) of HCV infection in the world, and particularly in Italy.