Serum samples from 222 Somalian patients, 135 with the lepromatous form of leprosy and 87 with the tuberculoid form of the disease, were examined for the presence of the surface antigen (HBsAg), the "e" antigen (HBeAg), and their corresponding antibodies (anti-HBs and anti-e). HBsAg was present in 24.4% of the LL cases and in 11.5% of the TT patients while anti-HBs was found respectively in 46.6% and 58.6%. The e-antigen was not found in any case of leprosy; anti-e was detected in 8.1% of the LL patients and in 3.5% of the TT cases. The rate of HBV seropositivity (HBsAg plus anti-HBs) was the same in the LL patients (71.1%) and in the TT patients (70.1%) and that could reflect the conditions of life in their closed community. The analysis of results obtained in Somalia has shown the presence of a difference in the distribution of HBsAg among leprosy patients, with an increased antigenemia in the lepromatous form which was statistically significant (p less than 0.05). No differences, however, were found between the leprosy patients and healthy controls. These observations seem to indicate that patients with lepromatous leprosy do not have an increased susceptibility to infection by hepatitis B virus.