For at least a decade after the licensure of vaccines to prevent major childhood diseases, incidence of these diseases decreased. However, in the mid-to-late-1980s, four major childhood illnesses showed increases in the number of cases and the case rate, and the United States experienced epidemics of measles, mumps, rubella and whooping cough. The measles epidemic was the most severe of the four with over 55,000 cases, 11,000 hospitalizations, and 130 deaths reported across the country between 1989 and 1991. Children were hit the hardest by these epidemics. Predating these epidemics was a decline in the immunization levels of 2-year-olds. This decline coincided with vaccine price increases, an increase in the percentage of children in poverty and a decline in the rate of poor children receiving Aid to Families with Dependent Children (AFDC) and Medicaid. An estimated 100,000 excess cases of disease resulted from the low levels of immunization and consequent epidemics. While immunization rates have increased in recent years, it is important to continue our progress in this area in order to protect children from vaccine-preventable infectious diseases.