Six hundred and thirty-two blood samples from 879 consecutive admissions to one resettlement camp for Indochinese refugees in Great Britain were screened for markers of hepatitis B (HB) virus infection. The overall prevalence of HB surface antigen (HBsAg) was 15%, being 16% in those aged 40 years or less, and falling to 8% in those older than 40 (P less than 0.05). No significant difference in prevalence was found between males and females. HBe antigen was detected in 56% of those with HBsAg and was demonstrable in 55-76% of those under 30 years of age. HBe antibody was found in 21% of HBsAg-positive refugees. In those under 40 years old, HB core (HBc) antibody was commoner in males (P less than 0.01). HBc antibody prevalence increased significantly with age in females (P less than 0.01) but not in males. There was no definite evidence that vertical transmission of hepatitis B was present in the group studied.