Clinical and epidemiologic data point to a causal interrelationship between nutritional deficiency and infectious illness. Both are major contributors to childhood morbidity and mortality, particulary in underprivileged population groups. Protein-calorie malnutrition depress a variety of immune funtions. Delayed hypersensitivity and number of T-lymphocytes are consistently reduced. The interrelationship between nutritional status and immune response was studied in 80 children aged under 6 years. According to the anthropometric assessment based on weight for height for age, 36 children were classified as normal, 22 as morderate malnutrition, and 22 as severe malnutrition. The following determinations were made : hemeglobin, hematocrit, serum albumin, immunoglobulin G, complement 3, and WBC levels. Results indicate that levels of Hb, Hct, serum albumin, and C3 concentration were decreased in moderate and severe malnutrition children. However, levels of IgG and WBC were not affected by the nutritional status. It is suggested that nutritional status has more profound effects on complement system than humoral immunity.