Vaccination has dramatically reduced the number of annual cases of pertussis, diphtheria, measles and congenital rubella syndrome. Although side effects of immunizations can occur, serious adverse events are rare for all vaccines commonly used in the United States. Infantile spasms and sudden infant death syndrome are not associated with childhood vaccines. Compared with whole-cell pertussis vaccine, acellular pertussis vaccines are significantly less likely to produce moderate reactions such as fever, fussiness, pain, drowsiness, anorexia and local redness or swelling. Despite the documented safety and efficacy of childhood vaccines, concerns about vaccine safety increase when diseases such as measles, pertussis and rubella are no longer common. Parents need to be reminded that their child is susceptible to these diseases, that these diseases are preventable by reasonably safe and effective immunizations and that their child needs a series of vaccines at regular intervals by the age of two years. Since 1994, all physicians have been required by law to use the Vaccine information Statements for measles-mumps-rubella vaccine, diphtheria and tetanus toxoids and pertussis vaccine, poliovirus vaccines and tetanus and diphtheria toxoids for adults.