- Hepatitis B is a major problem worldwide. Israel has intermediate endemicity for hepatitis B virus, and an annual carrier rate of 1-3%. To evaluate both the prevalence of HBV infection among family members of HBV carriers and the competence of family practitioners in performing a comprehensive assessment. A total of 152 HB surface antigen-positive blood donors were discovered in our subdistrict during the years 1993-97. Their family physicians were questioned regarding the patients' family members. Specific information on 85 spouses and 200 children was also obtained. Among the 85 married carriers, 5 of the spouses (5.9%) were found to be HBsAg positive. None of the 200 children was HBsAg positive. We found that in a third (n = 52) of the patients, the sexual partner had never been tested by a primary care physician. Patients were not routinely tested for HB e antigen or anti-HBe antibodies. Neither the parents nor the siblings had undergone any serological evaluation. However, most family members of the carriers had received an HBV vaccine from their family physicians. Our findings show that horizontal transmission of HBV among spouses of HBV carriers still exists. We did not find any vertical transmission, probably due to male predominance and previous vaccination. Family physicians should be trained to perform an extensive serological evaluation of family members of patients with chronic HBV infection, including parents and siblings, and should vaccinate seronegative family members.