People with intellectual disability are a well-known high-risk group for hepatitis B virus (HBV) infection. Hepatitis B virus is a major public health problem, but it is often neglected because of its largely asymptomatic course with long-term complications. Safe and effective vaccines have been available for over 15 years. However, universal vaccination strategies have not or have not completely been implemented to date, even though epidemiological data have indicated the effectiveness and efficacy of vaccination, and economic evaluations have shown that it is cost effective. Hepatitis C virus (HCV), which was discovered in 1989, has similar risk factors and is also a cause of chronic hepatitis. The prevalence of HCV amongst individuals with intellectual disability has not been clearly established. An overview of the literature on the prevalence of HBV and HCV in this population, as well as risk factors, transmission and prevention is presented in the present review. The literature cited in the present article was obtained by searches in MedLine using the following keywords and keyword combinations: hepatitis, hepatitis B virus, hepatitis C virus, mentally retarded, mentally handicapped, developmentally retarded, intellectual disability, institutionalization, Down's syndrome and hepatitis B vaccination. The search was done from 1980 to 1998. Beside this, the older articles found in the references were included if these were considered necessary for completeness.