Acute type B viral hepatitis developed near the term of pregnancy in seven women. All had signs of acute hepatitis at delivery, and hepatitis B surface antigenemia persisted two to four weeks after delivery. Two milliliters of conventional immune human serum globulin was administered to the neonates within a week of birth, after preexisting type B viral hepatitis infection was excluded. The antibody against hepatitis B surface antigen (anti-HBs) content of two of the administered batches of immune human serum globulin was 1:32 and 1:64. None of the babies became hepatitis B surface antigen carriers, and anti-HBs developed without obvious clinical hepatitis in one baby. Conventional immune human serum globulin in larger doses may be a relatively safe and effective prophylaxis against the development of hepatitis B surface antigen carrier state even if the anti-HBs content in the administered dose is relatively small. (JAMA 236:2302-2304, 1976)