This multi-centre, cross-sectional study was designed to reveal the present status of hepatitis B infection markers among Lebanese children, and provide recommendations regarding childhood immunization policies. A total of 841 children, aged between 6 months and 6·5 years, were enrolled from Lebanon's five districts. Their sera were tested for hepatitis B surface antigen and hepatitis B core IgG. The overall prevalence of hepatitis B virus infection markers was 0·8 % with increasing age-specific rates from 0 % at 6 months to 1·3 % at > 5 years. There was no statistically significant association between the presence of hepatitis B markers and family characteristics or risk factors for infection. The highest prevalence rates were among children from Beirut suburbs (2·9 %) and South Lebanon (1·6 %). The risk of horizontal transmission of hepatitis B to uninfected children increased substantially after the age of 2 years. An expanded programme on immunization that integrates hepatitis B vaccine during the first year of life is needed.