During the two year period 1986/87, 271 babies were born to hepatitis B surface atigen carrier mothers in the English West Midlands. Babies were allocated sequentially into either treatment Group A (4 doses of HBVax, Merck Sharp & Dohme, 10 mcg. i.m, at birth, 1, 2 and 6 months) or treatment Group B (250 I.U. hepatitis B immunoglobulin (HBIG) at birth, combined with the same vaccine schedule as Group A). 172 babies were enrolled and data was available for analysis on 150 (87%).Results:ConclusionsIn circumstances in which HBIG is not available a 4 dose vaccine schedule can protect at risk infants from perinatal transmission of HBV. In babies born to the less infectious carrier mothers in our study (i.e. those not HBe Ag+) the addition of HBIG to the schedule conferred no added benefit. In infants born to HBe Ag+ mothers protection was enhanced by addition of HBIG although transmission was still not prevented in every case. In utero infection and slow response to vaccine may be implicated failure mechanisms.