The aim of this study was to assess the efficacy of Chagas disease vector control in Chile, using human disease as an index. After a twelve years control program using insecticides, dwelling infection in the IV region fell from 49 to 4%. In Combarbalá (a community of the IV region) the infection rate, detected by indirect hemagglutination, immunofluorescence and ELISA tests, decreased from 21.8% in 1986 to 8.2% in 1992 in primary school students (p < 0.001) and from 7.5 to 5% in high school students. Besides the vector control program, no other important epidemiological changes occurred in this period, excepting some ecological changes.