Nutritional deficits commonly occur in patients of all ages suffering from chronic inflammatory bowel diseases. Growth failure represents a common, serious complication unique to the pediatric age group. Although the etiology of nutritional problems and growth failure is multifactorial, malnutrition owing to inadequate nutrient intake is the primary cause. Nutritional supplementation via the enteral or parenteral route restores normal body composition and can reverse linear and ponderal growth failure if administered effectively and prior to bone maturation. Both parenteral and enteral nutrition have been shown to effectively induce remission in acute Crohn's disease, but appear to be less satisfactory for patients with ulcerative or Crohn's colitis. The mechanisms by which such nutritional therapies improve disease activity are unclear but may involve the intestinal adaptive response to "bowel rest," immunologic effects, and nutritional factors.