Nutritional status affects every pediatric patient's response to illness. Good nutrition is important for achieving normal growth and development. Nutritional assessment therefore should be an integral part of the care for every pediatric patient. Routine screening measures for abnormalities of growth should be performed on all pediatric patients. Those patients with chronic illness and those at risk for malnutrition should have detailed nutritional assessments done. Components of a complete nutritional assessment include a medical history, nutritional history including dietary intake, physical examination, anthropometrics (weight, length or stature, head circumference, midarm circumference, and triceps skinfold thickness), pubertal staging, skeletal maturity staging, and biochemical tests of nutritional status. Alternative measures for linear growth assessment (e.g., lower leg and upper arm measures) can be performed on patients unable to stand or who have musculoskeletal deformities. Bone densitometry can be used to assess bone mineralization and the risk of fracture. Nutritionally at risk patients may benefit from determination of resting energy expenditure by indirect calorimetry. The use of age, gender, and disease-specific growth charts is essential in assessing nutritional status and monitoring nutrition interventions. The importance of accurate measurements using trained personnel and appropriate equipment cannot be overemphasized.