The fast rate of increase in the number of older people in less-developed countries threatens to further strain the limited health resources of these countries. However, very little is known about their health status and the risk factors that contribute to it. In this article, we review the burden of infectious diseases in elderly people in less-developed countries, discuss the contribution of nutrition and immune response to morbidity and mortality, identify gaps in current knowledge, and suggest strategies to address this fast-growing public health problem.