PIP: Accurate prevalence and incidence figures do not exist on a global basis, yet available data suggest that acute respiratory infections in children represent a problem of enormous magnitude. World Health Organization (WHO) data from 88 countries representing 1/4 of the world's population indicate that there are over 666,000 deaths annual from acute respiratory infections. Assuming that nonreporting countries have similar mortality rates, it can be calculated that there are at least 2.2 million deaths from acute respiratory infections throughout the world each year. Despite the enormity of the problem, relatively little is known about the factors that contribute to these deaths in children or adults, or about the extent to which they are due to unusual severity of the disease, lack of access to the health care system, and institutional or social factors. The causative agents are unknown. More knowledge is needed to mount an effective program for the prevention and treatment of acute respiratory infections. In Costa Rica mortality from this disease is 12 times higher in malnourished infants than in those of normal weight. Data from Papua, New Guinea indicate that Streptococcus pneumoniae and Hemophilus influenzae are common etiologic agents. More data of this kind are needed from different countries. Also needed is information on the availability and use of adequate medical care. People in developed countries run a greater risk of dying from lung cancer and cardiovascular diseases than do people in developing countries, but the chances of dying from acute respiratory infections generally exceed those of dying from lung cancer or cardiovascular disease in the developing countries. When evaluating the seriousness of a public health problem it is important to consider the number of years of life that have been lost as well as morbidity and mortality. If there are 2.2 million deaths in the world from acute respiratory infections in children under the age of 1 year, then each year there are almost 200 million death years lost because of acute respiratory infections in the world. Thus, on a global scale acute respiratory infections represent a public health problem of greater magnitude than either heart disease or cancer. The fact that the annual WHO budget for heart disease is at least 50 times higher than the budget for all forms of respiratory disease represents seriously misplaced priorities. Properly organized research programs into the etiologic agents involved in acute respiratory infection, together with data collection on other contributing factors, are required so that effective prevention and treatment programs can be initiated.