Nutritional deficiencies are associated with altered immune responses and increased susceptibility to infection. The changes are most marked in severe deficits of nutrient intake and some nutrients are more critical than others in influencing immunity. Similarly, there is a correlation between body size and immunocompetence. Both protein-energy malnutrition and obesity are associated with changes in selected parameters of immunity. Very little is known about changes in immune responses in stunting. These effects of nutritional status and of body size and composition may be mediated through changes in hormones, cytokines and/or cell number and function.