Hepatitis B virus (HBV) is transmitted via blood or sexual contact. Persons with chronic HBV infection are at increased risk for cirrhosis and liver cancer and require medical care. This report updates and summarizes previously published recommendations from the Advisory Committee on Immunization Practices (ACIP) and CDC regarding the prevention of HBV infection in the United States. ACIP recommends testing all pregnant women for hepatitis B surface antigen (HBsAg), and testing HBsAg-positive pregnant women for hepatitis B virus deoxyribonucleic acid (HBV DNA); administration of HepB vaccine and hepatitis B immune globulin (HBIG) for infants born to HBV-infected women within 12 hours of birth, followed by completion of the vaccine series and postvaccination serologic testing; universal hepatitis B vaccination within 24 hours of birth, followed by completion of the vaccine series; and vaccination of children and adolescents aged <19 years who have not been vaccinated previously. ACIP recommends vaccination of adults at risk for HBV infection, including universal vaccination of adults in settings in which a high proportion have risk factors for HBV infection and vaccination of adults requesting protection from HBV without acknowledgment of a specific risk factor. These recommendations also provide CDC guidance for postexposure prophylaxis following occupational and other exposures. This report also briefly summarizes previously published American Association for the Study of Liver Diseasest guidelines for maternal antiviral therapy to reduce perinatal HBV transmission.