This revision of the General Recommendations on Immunization updates the 1989 statement. Changes in the immunization schedule for infants and children include recommendations that the third dose of oral polio vaccine be administered routinely at 6 months of age rather than at age 15 months and that measles-mumps-rubella vaccine be administered routinely to all children at 12-15 months of age. Other updated or new sections include a) a listing of vaccines and other immunobiologics available in the United States by type and recommended routes, advice on the proper storage and handling of immunobiologics, a section on the recommended routes for administration of vaccines, and discussion of the use of jet injectors; b) revisions in the guidelines for spacing administration of immune globulin preparations and live virus vaccines, a discussion of vaccine interactions and recommendations for the simultaneous administration of multiple vaccines, a section on the interchangeability of vaccines from different manufacturers, and a discussion of hypersensitivity to vaccine components; c) a discussion of vaccination during pregnancy, a section on breast-feeding and vaccination, recommendations for the vaccination of premature infants, and updated schedules for immunizing infants and children (including recommendations for the use of Haemophilus influenzae type b conjugate vaccines); d) sections on the immunization of hemophiliacs and immunocompromised persons; e) discussion of the Standards for Pediatric Immunization Practices (including a new table of contraindications and precautions to vaccination), information on the National Vaccine Injury Compensation Program, the Vaccine Adverse Events Reporting System, and Vaccine Information Pamphlets; and f) guidelines for vaccinating persons without documentation of immunization, a section on vaccinations received outside the United States, and a section on reporting of vaccine-preventable diseases. These recommendations are based on information available before publishing and are not comprehensive for each vaccine. The most recent Advisory Committee on Immunization Practices (ACIP) recommendations for each specific vaccine should be consulted for more details.