The family members of HBsAg carriers have an increased risk of hepatitis B virus (HBV) infection. 214 subjects from 98 families with no HBV markers were randomized to receive hepatitis B vaccine: HEVAC B (Institute Pasteur) or GCC VAC (Green Cross Corporation) at 0, 1, and 5 months. Of those who completed the course, 87.8% had an anti-HBs response of greater than 10 mIU/ml at 6 months. The response rate was similar for both sexes. There was a decrease in response rate and anti-HBs titre with age. The response rate for HEVAC B was 92.5% and GCC VAC 84.3%. The offspring had comparable response to the spouses who were not blood relatives of the index carriers, but this could be related to their younger age. Discriminant analysis showed that a higher anti-HBs titre was associated with HEVAC B, younger age, and less direct relationship with the index carrier.