Chronically severe illness patients typically suffer from malnutrition, and patients with respiratory failure have much higher risk to experience malnutritional condition. There are only a few researches discussed on the nutritional care of patients with respiratory failure in Taiwan, and articles about recommendations for suitable nutrition assessment tool are even less. The purposes of this article are to provide an introduction and comparison of different nutrition assessment and screening tools for clinical use. If we can detect early stage malnutrition status and support clients with appropriate nutritional care, then we can improve the quality of medical care and decrease the heavy burden to the society.