Injecting drug users are at high risk of acquiring blood-borne infections. Ireland has had a harm reduction policy of methadone maintenance and needle exchange since 1992. The aim of this paper is to estimate prevalence of hepatitis B, hepatitis C and HIV infection and appropriate uptake of hepatitis B vaccine in methadone attendees and to make recommendations for a simple record-based surveillance system. The study involves a retrospective study of 138 client records for evidence of laboratory tests or test results for blood-borne viruses and appropriate immunisation against hepatitis B. A total of 60% of clients had evidence of one or more laboratory tests in their notes. Of those tested for individual viruses, 5.1% were positive for hepatitis B surface antigen, 78.8% had antibodies to hepatitis C and 16.7% were HIV positive. Nearly two-thirds of clients had no evidence of vaccination or information on prior immunity in their records. The authors concluded that a standardised written protocol for screening for blood-borne viruses and for immunisation against hepatitis B in methadone service attendees was clearly needed, and was subsequently introduced by the Eastern Region Health Authority.