Assessment and monitoring of protein and energy nutritional status are essential to prevent, diagnose, and treat uremic malnutrition, a condition highly prevalent and associated with increased morbidity and mortality in patients with advanced kidney failure. Comprehensive assessments of protein and energy nutritional status can be achieved by several measurements to quantitatively and qualitatively estimate protein content in visceral and somatic body compartments, in addition to measurements of energy balance. However, uremic malnutrition is a complex metabolic disorder in which not only net nutrient intake is lower than nutrient requirements, leading to decreased tissue function and loss of body mass, but it is also associated with many comorbid conditions. Therefore, a clinically meaningful assessment of uremic malnutrition should include methods that are able to assess clinical outcome, identify the underlying diseases, and determine whether there is potential of benefit from nutritional interventions. Such assessment usually requires using multiple measurements concomitantly, with no definitive single method that can be considered as a "gold standard." In this review, we describe the various types of methods to assess uremic malnutrition, expanding and updating data on the readily available methods, and discuss more precise techniques to estimate protein and energy homeostasis. Special considerations of specific methods related to their clinical and/or research applicability as they pertain to renal failure are also addressed.