The provision of artificial nutrition for critically ill patients is of great importance as many are unable to maintain their own nutritional needs. The administration of total parenteral nutrition (TPN) and enteral nutrition (EN) has become a daily practice in intensive care units. Despite this, many patients remain undernourished or even malnourished and it is estimated that the incidence of malnutrition in intensive care patients could be as high as 50% (McCain, 1993). The reasons by which patients become or remain undernourished are multifactorial and range from physiological to iatrogenic. In order to lessen the catabolic state which results from the hypermetabolism associated with critical illness, prompt and adequate nutritional support must be delivered. It is essential that members of the multidisciplinary team caring for critically ill patients are aware of the importance of nutrition and the deleterious effects of malnutrition to achieve the best possible outcome for patients.