Prevalence of HBsAg was studied by counterelectrophoresis (CEP) in 65,795 consecutive volunteer blood donors in Israel. The overall prevalence of HBsAg was 1.22%. HBsAg was more prevalent in the young donors, more prevalent in male donors and varied according to the country of origin of the donors. The prevalence of HBsAg was 0.63% among donors born in Europe or the Americas and 2.83% for those born in Asia or Africa. The HBsAg prevalence among native Israelis followed the same pattern with higher prevalence rates among those born in Israel whose families came from Asia or Africa than those from Europe or America. The prevalence of Anti-HBS by CEP was studied in 39,519 donors. The prevalence of antibody was higher in females and was higher in the same ethnic groups in whom there was a relatively high HBsAg prevalence.