To provide a comprehensive understanding of the epidemiology of hepatitis C virus (HCV) infection in Scotland, a database of all persons known to have been infected with HCV in Scotland was established. Non-identifying data, held on the computers and requests forms in Scotland's principal and confirmatory HCV testing laboratories, were entered onto a National Database at the Scottish Centre for Infection and Environmental Health. As at December 2001, records from 13,519 persons in Scotland known to have been infected with HCV had been entered on to the database (one in 378 of Scotland's population). Of the 13,519, 69% were male and 90% of the 9,092 for whom risk factor information was available had injected drugs; 37% were from Greater Glasgow. Fifty-six per cent of the 13,519 were diagnosed between 1998 and 2001; 1,727 (23%) of the new diagnoses from 1998 to 2001 were aged under 25 years. The data provide an insight into the epidemiology of HCV infection in Scotland. They support other data, which indicate that the current major risk factor for HCV in the country is injecting drug use.