Infant mortality rates in Latin America are high. A thorough study of its causes and different aspects in several areas would be feasible only through coordinate continental investigations such as the "Inter American Investigation of Mortality in Adults". The Pan American Health Organization is carrying out a study named "Interamerican Investigation of Childhood Mortality", in 13 areas of Latin America, to investigate deaths of children of less than 5 years of age. These deaths are studied through interviews with the families, doctors and hospitals which were in contact with the children during the period of illness that led to death. Thus, data and information are obtained, with relation to the basic and related causes of death, as well as an evaluation of the nutritional state of the children. Simultaneously, an investigation is made on alive children of less than five years of age, through a random sampling technique of the houses in the area of study. São Paulo participates in this Investigation through the Department of Applied Statistics of the University of São Paulo School of Public Health. The area of study includes the district of the Capital, which contains 93% of the population of the entire county.