Hepatitis B virus (HBV) circulation was surveyed in three Somalian villages (Buur-Fuul, Mooda-Moode and Bajuni Islands) in different districts and 52 children living in a closed community, aged under one year, were studied. Of the 331 village subjects aged one to 83 years, 12.08% were HBs positive, 29.9% anti-HBs positive, 43.8% anti-HBc positive and 21.4 anti-HBe positive. Among the HBs-positive subjects, 34.7% had HBeAg and 21.7% had anti-HBcAg-IgM. No statistically significant differences were found for HBs, anti-HBs, anti-HBc and anti-HBe among the three villages. HBeAg prevalence was higher in Buur-Fuul than in Mooda-Moode and in Bajuni Islands. HBsAg prevalence was about the same for each age group studied, whereas the prevalence of anti-HBc showed a continuous rise and reached its maximum level of 43.8% in those aged 39 years and older. The proportion of HBs-positive subjects who also carried HBeAg was high in the youngest children but fell with age. HBs-positive children aged under one year had a high anti-HBc-IgM prevalence. Our finding suggests that perinatal infection may play an important role among the Somalian population in determining the reservoir of virus carriers.