this paper describes and examines the activities for the prevention and control of acute respiratory infections (ari) carried out by a pediatric program in a government health service that provides care to a low-income population in santiago, chile. the study area has a population of just over one million people and is served by one general hospital, 16 primary care clinics, and eight rural health posts. specific activities carried out by the ari program include personnel training as well as control measures at the primary care level and hospitalization of children with severe ari. in the first 5 years of the program (1990-1994), a reduction in annual mortality from pneumonia from 3.0 to 1.7 per 1 000 was observed among children under the age of one year, which contributed to a decline in infant mortality from 13.5 to 8.9 deaths per 1 000 live births. in 1994, program costs amounted to us$ 224 000. judging from the results obtained, the ari prevention and control program has made a valuable contribution in the area of child health.