Health-care workers are known to be at risk from occupational transmission of blood-borne viruses, including hepatitis C. There may be serious implications following infection with hepatitis C including possible transmission to patients. We determined the prevalence of hepatitis C virus (HCV) antibodies among health-care workers at risk of occupational contact with blood and body fluids and among source patients in reported blood-exposure incidents. Anonymised stored blood samples from health-care workers immunised against hepatitis B virus since 1991 (n = 1053) and blood samples from source patients in needlestick injuries (retrospective and prospective) since 1989 (n = 373) were analysed. 3 (0.28%) of the serum samples from health-care workers were found to be anti-HCV-positive. 17 (8.5%) of 200 source patients tested retrospectively between January 1989 and January 1992, and 24 (13.9%) of 173 source patients tested prospectively between January 1992 and June 1993 were anti-HCV-positive. During the second period, 15 (10.6%) of 142 source patients tested for human immunodeficiency virus (HIV) were positive and 7 (3.8%) of 184 source patients tested for hepatitis B surface antigen were positive. 6 of 24 (25%) HCV-infected patients were diagnosed only after the incident; for hepatitis B, 2 (33%) of patients were diagnosed after the incident, and for HIV all patients were previously diagnosed. The seroprevalence of HCV among these health-care workers is no higher than that reported in blood donors.(ABSTRACT TRUNCATED AT 250 WORDS)