Sera from 95 children below 20 years of age born to Assyrian immigrants were tested for markers for hepatitis B virus (HBV). HBV markers were found in 26% of the study population. However, no markers were demonstrated in children born in Sweden. Of the 62 children born in Turkey or the Middle East 39% had HBV markers and 4 (6.5%) had HBsAg. Three of the 4 HBsAg+ children had anti-HBe and 1 HBeAg. These results suggest that the transmission of HB in Assyrians may be mainly horizontal rather than vertical. Children of Assyrian immigrants born in Sweden do not seem to constitute a risk group for transmission of HB, whereas those born in Turkey or the Middle East constitute the same risk as reported in a general population of Turks.