BACKGROUND: In 2004, the Moldovan government introduced mandatory (social) health insurance (MHI) with the goals of sustainable health financing and improved access to services for poorer sections of the population. The government pays contributions for non-employed groups but the self-employed, which in Moldova include many agricultural workers, must purchase their own cover. This paper describes the extent to which the Moldovan MHI scheme has managed to achieve coverage of its population and the characteristics of those who remain without cover. METHODS: The 2008 July-October enhanced health module of the Moldovan Household Budget Survey was used. The survey uses multi-stage random sampling, identifying individuals within households within 150 primary sampling units. Numbers and characteristics of those without insurance were tabulated and the determinants of lack of cover were assessed using multivariate regression. RESULTS: 3760 respondents were interviewed. Seventy-eight per cent were covered by MHI. Factors associated with being uninsured include being self-employed (particularly in agriculture), unemployed, younger age and low income. Respondents who were self-employed in agriculture were over 27 times more likely to be uninsured than those who were employed. Agricultural workers in Moldova are responsible for purchasing their own cover; most respondents cited cost as the main reason for not doing so. CONCLUSION: While being uninsured has an impact on utilization, financial barriers persist for those with insurance who seek care. The strengths and weaknesses of the MHI system in Moldova provide valuable lessons for policy makers in low- and middle-income countries addressing the challenges of achieving equitable coverage in health insurance schemes and the complex nature of financial barriers to access.