The nutritional status of an individual has a profound effect on both host susceptibility to specific infectious diseases and on their outcome. Available data suggest that specific and aggregate nutritional deficiencies can alter a host's immune response and increase susceptibility to infection. From a nutritional point of view, the process of nutrient loss and redistribution has the potential for being exploited to the benefit of the infected malnourished host. The proposal to use nutritional support to bolster the host response to infection in severely ill malnourished patients gains support from the fact that this reiterative cycle of malnutrition and infection is the main cause of morbidity and mortality in children in underdeveloped countries.