Nutritional assessment is an integral part of optimal pediatric care. Undernutrition, which may be primarily due to inadequate food intake or secondary to infection, injury, or disease, is the most important cause of growth retardation in children. Comprehensive nutritional assessment involves evaluation by clinical, anthropometric, biochemical, and dietary methods. Nutritional parameters include those reflecting changes in body size, composition, and/or function. All patients should be nutritionally screened. If malnutrition is suspected, comprehensive nutritional assessment should be performed.