The prevalence of hepatitis B viral markers was studied in 673 women of childbearing age in 17 villages (12 indigenous and five plantation villages) on the north coast of Papua New Guinea. Some 7.9% of women were HBsAg positive and 41.3% were positive for anti-HBs. There was significant variation in prevalence between villages, ranging from 0 to 13.9% for HBsAg and 26.0 to 71.0% for all markers. The 12 indigenous villages were classified into three groups according to language (Austronesian or non-Austronesian), location (inland or coastal), and marriage patterns. The prevalence of hepatitis B was significantly higher in Austronesian than in non-Austronesian villages (P less than 0.01), and it remained significant after controlling for age differences and for possible effects on prevalence caused by women marrying into the three village groups from other areas. Interactions between malaria and hepatitis B were also investigated. Non-Austronesian villages with the highest spleen rates had the lowest prevalence of hepatitis B infection, and there was no correlation with parasitaemia. These results may reflect a lower exposure of women to hepatitis B infection in non-Austronesian villages, or may indicate different genetic or immunological responses to infection between Austronesians and non-Austronesians.