One hundred thirty-two newborns of carrier mothers were given combined passive-active immunization against the hepatitis B virus. Doses of hepatitis B immunoglobulin (HBIG) were 0.5 ml, and doses of vaccine (Heptavax B) were 10 micrograms. Schedules used were: HBIG, 0, 3 and 6 months and vaccine 1, 2 and 7 months (Schedule 1); HBIG, 0, 3 and 6 months, vaccine, 7, 8 and 13 months (Schedule 2); HBIG, 0 month and vaccine 1, 2 and 7 months (Schedule 3); HBIG, 0 month and vaccine 0, 1 and 6 months (Schedule 4). The study population consisted of 60 boys and 72 girls. Ethnic origins were the following: Haitian, 42; Cambodian, 33; French Canadian, 22; Vietnamese, 21; others, 14. Thirty-two children were born to hepatitis B e antigen-positive mothers. General outcome was: 121 became anti-hepatitis B surface antigen-positive; 5 became hepatitis B surface antigen-positive; and 6 remained negative for all markers (nonresponders). Sex, ethnic origin and immunization schedule had no influence on the outcome. Of the 32 children born to hepatitis B e antigen-positive mothers, only 4 became hepatitis B surface antigen-positive. In those who became anti-hepatitis B surface antigen-positive, mean serum anti-hepatitis B surface antigen antibody concentrations (log mIU/ml +/- SD) were: 3.47 +/- 1.03 at 8 to 9 months post-Vaccine 1; 2.89 +/- 0.91 at 14 to 17 months; 2.39 +/- 1.0 at 23 to 29 months; and 2.26 +/- 0.92 at 35 to 41 months.(ABSTRACT TRUNCATED AT 250 WORDS)