The different uses of nutritional assessment are briefly reviewed. The parameters of nutritional assessment should be determined according to the use for which they are intended, such as nutritional epidemiology, preoperative assessment of nutritional risk, or nutritional monitoring during parenteral or enteral feeding. The roles of some nutritional variables that are used to identify and monitor high-risk patients during nutritional repletion are examined. The main questions that confront the clinician are as follows: (1) are the nutritional indicators of surgical risk altered by poor intake of nutrients? (2) can these indicators be normalized with adequate feeding or are they abnormal as a result of the metabolic impact of the disease? (3) are these variables simple indicators of surgical risk or are they directly involved in the host-defense mechanism? The importance is stressed of an integrated assessment of the patient's status when nutritional support is considered. This involves not only the static evaluation of the nutritional support according to standard parameters, but also a prospective and dynamic evaluation of nutrient requirements, length of hospital stay, and the curability of the basic disease.