Aim. This paper is a report of a study conducted to compare knowledge of hepatitis C virus infection amongst three groups of registered nurses working in primary care, to identify their current sources of information and access to educational resources.Background. Hepatitis C virus infection is a public health problem; no vaccine exists to prevent the disease. Previous studies identified limitations in nurses' knowledge of hepatitis C virus infection and the impact on care. Limited research has been conducted in primary care.Methods. A cross-sectional postal census survey of 981 nurses working in one Irish health board region was conducted March-June 2006. Questionnaires measured knowledge of hepatitis C virus infection. Data were collected on demographics, current working practices, information resources and previous education.Results. The response rate was 57.1% (n = 560). A minority (27.3% 145/531) of respondents agreed they were well informed about the virus. Almost 40% reported having contact with clients with the virus; however, information and service provision differed. Factors influencing higher knowledge included: contact with clients with hepatitis C virus infection (P < 0.0001), working in the addiction services (P < 0.0001), educated to degree level and above (P < 0.010) and previously attending education programmes (P < 0.0001). Only 21.5% (119/553) of respondents had attended any form of education on hepatitis C virus infection.Conclusion. Gaps in nurses' knowledge exist and can limit information and advice. Educational and information resources need to be developed for registered nurses working in primary care; care for clients with hepatitis C virus infection is not the sole remit of the addiction services. © 2010 Blackwell Publishing Ltd.