A community-based cross-sectional household seroepdemiological survey was conducted in the Republic of Yemen to estimate the prevalence of HBV infection as well as hepatitis B vaccine coverage and effectiveness amongst children vaccinated in the country's Expanded Programme on Immunisation (EPI). Study subjects were randomly selected from five provinces in the country based on probability proportional to size. The prevalence of HBV chronic infection amongst women of childbearing age participating in the survey was 5.08% and places Yemen amongst the group of countries with a high endemicity of HBV infection (> 5%). This is much lower than earlier estimates by hospital-based studies in Yemen estimating the prevalence of HBV chronic infection to be 12.5-16.6% amongst women of childbearing age. This prevalence estimate is more consistent with research findings from other neighbouring Middle East countries. There was evidence that perinatal transmission is not a major mode of HBV infection in Yemen. This is mainly the result of the low prevalence of HBV chronic infection amongst women of childbearing age (5.08%), the low prevalence of hepatitis B e antigenaemia (HBeAg) (12.84%) amongst HBV chronic carrier women, and the low infectivity (21.14%) ofHBeAg positive chronic carrier mothers. The prevalence of children completely vaccinated with hepatitis B vaccination was 8.63%. This estimate is lower than hepatitis B vaccination coverage estimates presented by the EPI in Yemen. The prevalence of incompletely vaccinated children was 12.47%. If these children completed their vaccination schedule, this would have increased the proportion of completely vaccinated children to more double than its current level. There were differences in hepatitis B vaccine coverage by area/province of residence indicating inequitable distribution, availability or accessibility to health services, with a bias towards better provision, or at least uptake of immunisation services in urban areas. Hepatitis B vaccine was found to be highly immunogenic and effective in preventing HBV infection amongst children aged 1-3 participating in the survey. In conclusion, this research demonstrates that HBV infection is not as major a public health problem in Yemen as originally expected, and this misconception needs to be corrected. Hepatitis B vaccine coverage, on the other hand, is low and must be increased. There is no need to amend the current hepatitis B vaccine schedule. Nevertheless, vaccine coverage should be increased with an emphasis on a more equitable distribution, access, and availability of hepatitis B vaccines.