Mortality from acute diarrheal diseases in Cuban children under 5 for the period 1959-1987 is analyzed. The data come from the Public Health Ministry's National Bureau of Statistics and other sources. The death rate in children under 5 declined from 28.5 per 10,000 in 1959 to 1.4 in 1987, or 95.1%. In the 1-4 age group it was reduced by 97.8%, and in those under 1 year, by 94.2%. In 1959 the deaths from acute diarrheal diseases represented 30.6% of all deaths in children under 5; 29.5% in those under 1 year, and 34.0 in those between 1 and 4. In contrast, by 1987 the respective figures had fallen to 4.1, 4.5, and 2.2%. The acute diarrheal disease situation in several countries of the Americas is stated for purposes of comparison and, finally, factors that have helped to lower mortality from this cause are analyzed as are other factors which will contribute to lower it in the future.