We critically review the various methods for assessing protein--calorie malnutrition. These tests are lacking in sensitivity and specificity, and currently no single one can be used as a reliable indicator of malnutrition. However, a combination of several of them can be used as prognostic indicators and are of help in selecting patients who may benefit from nutritional support. Body-composition analyses and functional tests hold the promise of greater applicability in the future. Newer and more nearly accurate tests for use in diagnosis of protein-calorie malnutrition as well as for objectively monitoring short-term changes in response to nutritional repletion are badly needed. Despite a lack of consensus on the desirability of objective nutritional assessment, we expect the use of these procedures in hospitals to increase.