Between 1979 and 1994, epidemiological surveillance of meningitides in Uruguay showed a progressive increase in suppurative meningitides due mainly to Neisseria meningitidis and Haemophilus influenzae type b (Hib). The cases were concentrated in children under 5; however, among the cases caused by Hib, 70% affected children from 1 to 11 months old. Facing this situation, the Ministry of Public Health resolved, as of August 1994, to include the Hib vaccine in the country's Expanded Program on Immunization, which has been in place since 1982. The Hib vaccination is done without charge and is obligatory for all children under 5 years of age. It is done using the following series of vaccinations: a) three doses, given at 2, 4, and 6 months, with a booster dose at age 1; b) children from 7 to 11 months old receive two doses two months apart and a booster dose a year later; and c) a single dose for children 12 months to 4 years old. Between August and December 1994 a coverage rate of 76.6% was reached among children between 2 months and 4 years old, and the coverage has remained above 80% in the new cohorts. In Uruguay, this vaccination strategy had a spectacular impact on morbidity and mortality due to meningitides caused by Hib. One of the results was that the incidence of 15.6 per 100000 registered in children under 5 in the prevaccination years declined to 0.03 per 100000 in 1996.