Various functional parameters involved in resistance to infection were investigated in children suffering from varying grades of protein-calorie malnutrition. It was observed that the phagocytic function was impaired in children whose weights were below 80% of the Indian Council of Medical Research standard, whereas the cell-mediated immune response was altered in those with weights below 70% of the standard. Antibody response to typhoid antigen was impaired in children with severe protein-calorie malnutrition, while the response to diphtheria and tetanus toxoids was normal in all. These observations suggest that malnourished children whose weights are below 80% of the Indian standard are likely to suffer from at least one functional handicap which may increase the risk of infection. In any action-oriented program, priority should, therefore, be given to this group of children.