Nutrition is a final common pathway in chronic disease, and weight loss is a major manifestation of acquired immunodeficiency syndrome (AIDS). In sub-Saharan Africa, studies have shown that 25% of children with malnutrition have human immunodeficiency virus (HIV) infection, although patterns of malnutrition are indistinguishable from those who are HIV negative. Breast-feeding increases the risk of vertical transmission, and the overall risk versus benefit needs continuing careful consideration in relation to local mortality from gastroenteritis and malnutrition. Chronic diarrhea is much more common in HIV-infected children in Africa and may have a multiplicity of causes, including infection with adherent forms of Escherichia coli, protozoa, and even direct HIV infection of intestinal mucosal cells. The HIV wasting syndrome produces reduction in bioelectrical impedence, fat, lean body mass, and body cell mass, but the changes can be predicted from equations used in starvation states. Micronutrients may be important, but observed changes may be due to immune mediator activation, rather than malnutrition. Calorie supplementation is beneficial when delivered by any route, but is likely to produce the greatest positive change when CD4 counts are highest in relation to calorie intake. Paradoxically, HIV-infected children may be obese early in the disease until AIDS develops. There is an inextricable link between disease and nutritional status. In children with AIDS wasting syndrome, a low CD4 count and high viral load are likely so that effective antiviral treatment may ultimately produce the greatest improvement in health, including nutritional status.