Tibetans have been living in Nepal since 1959. Study of the prevalence of viral hepatitis among them showed that they have a high prevalence of hepatitis B virus (HBV) infection. Prevalence of total HBV infection and Hepatitis B surface antigen (HBsAg) among them was 61% and 16% compared to 10.0% and 0.7% respectively among the Nepalese. The predominant HBsAg subtype among the Tibetans was 'ayw'. Perinatal and childhood transmission was found important in the spread of HBV infection among the Tibetans.