Nutritional support is the provision of nutrients to patients who cannot meet their nutritional requirements by eating standard diets. Nutrients may be delivered enterally (using oral nutritional supplements; nasogastric, nasoduodenal, and nasojejunal feeding tubes; and tube enterostomies) or parenterally (using lines or catheters placed in peripheral or central veins, respectively). Current nutritional support techniques permit adequate nutrient delivery to most patients. Nutritional support should be utilized, however, only if it is likely to improve the patient's clinical outcome. The financial costs and risks of complications must be balanced against the potential advantages of improved nutritional status in each clinical situation.